View source for Eponyms (M-P)

==M==
===Macaulay's disease===
Lymphomatoid papulosis, a low-grade cutaneous T-cell lymphoma. 

===MacCallum's plaques===
Irregular thickenings, usually in the left atrium, from subendocardial lesions, usually exacerbated by regurgitant jets. 

===MacConkey medium===
Medium for growing nonfastidious Gram-negative rods. 

===Macewen's sign===
In hydrocephalus before closure of sutures, cracked pot sound when percussing over dilated ventricles. 

===Machado-Joseph disease===
Spinocerebellar ataxia 3, named for affected families of Azorean origin, autosomal dominant disorder caused by a CAG expansion in gene on 14q, onset after age 40, associated with diabetes. 

===Mackler triad===
In [[esophageal rupture]], triad of vomiting, chest pain, and subcutaneous emphysema. 

===Macleod's syndrome===
Unilateral hyperlucent lung, see Swyer-James syndrome. 

===Maddrey discriminant function===
For predicting mortality in patients with alcoholic hepatitis, Maddrey DF = 4.6 x (PT-control PT) + serum bilirubin; DF > 32 associated with high short-term mortality, 1 month mort 35% in absence of encephalopathy and 45% if encephalopathy present. 

===Madelung deformity===
Growth disturbance in the volar-ulnar distal radius that results in bowing of the distal end of the radius, resulting in radius shorter than the ulna; presents mainly in adolescent females; also associated with variant of dwarfism, dyschondrosteosis. 

===Madelung's disease===
Benign symmetric lipomatosis; characterized by numerous, symmetrically distributed, non tender, poorly demarcated, fatty tumors; distributed mainly in vicinity of neck, sub-occipital region, proximal extremities, and upper part of trunk; can result in "horse-collar appearance." Also known as Launois-Bensaude syndrome. 

===[[Madura foot]]===
Actinomycetoma of the foot; chronic bacterial infection of subcutaneous tissue often due to traumatic injury (e.g. from walking barefoot). Nocardia usual organism. Madura is a city in southern India.

===Maffucci's syndrome===
Enchondromatosis associated with soft tissue hemangiomas; associated with ovarian carcinomas and brain gliomas; essentially Ollier's disease with hemangiomas. 

===Magendie, foramen of===
Midline foramen exiting out of fourth ventricle of the brain. 

===[[Maisonneuve fracture]]===
Spiral fracture of the proximal third of the fibula associated with ankle fracture (rupture of the distal tibiofibular syndesmosis associated with fracture of the tibia and rupture of the deltoid ligament); usually from ankle eversion injury. 

===Majocchi granuloma===
Infection of hair follicle from dermatophyte; foreign body granuloma most commonly due to Trichophyton rubrum infection, e.g. in young women who frequently shave their legs. 

===Majocchi's disease===
Purpura annularis telangiectodes. 

===Mallampati classification===
Score for predicting ease of intubation (1 through 4), higher score assocated with more difficult intubation and sleep apnea. 

===Mallory body===
"Alcoholic hyalin", an eosinophilic intracytoplasmic inclusion in liver cells that is characteristic of alcoholic liver disease but also seen in e.g., primary biliary cirrhosis, Wilson's disease, chronic cholestatic syndromes, focal nodular hyperplasia, and hepatocellular carcinoma. Inclusions composed largely of intermediate filaments of prekeratin. 

===[[Mallory-Weiss tear]]===
Small defects in gastroesophageal junction, from violent retching; originally described in the context of alcoholic gastritis, can lead to severe bleeding, 87% occur below gastroesophageal junction; bleeding stops 90% without intervention. 

===Malone procedure===
Creation of a continent appendicostomy or neoappendix as a conduit for irrigation of the colon as treatment for fecal incontinence due to pediatric anorectal malformations, spina bifida, chronic constipation, etc. as an alternative to rectal enemas. 

===Malta fever===
[[Brucellosis]]. Also known as Bang's disease. 

===Maltese cross===
Fat droplets in urine. 

===Mantoux test===
Test for [[tuberculosis]] with intradermal injection of purified protein derivative of tuberculin, 0.1 mL of 5 tuberculin units. 

===Maple syrup urine disease===
Deficiency in branched-chain alpha ketoacid dehydrogenase resulting in increased levels of branched chain alpha amino acids and alpha-keto analogs in plasma and urine, 1:200,000, high mortality. Urine has characteristic maple syrup smell. 

===Marburg's disease===
Acute form of [[multiple sclerosis]], fulminant and progressive. 

===[[Marburg virus disease]]===
Filovirus that causes [[hemorrhagic fever]]

===Marchiafava-Bignami syndrome===
Seen in malnourished alcoholics, necrosis of corpus callosum and subcortical white matter leading acutely to chronically to dementia, spasticity, dysarthria, gait disorder, and coma. 

===Marcus Gunn pupil===
Afferent pupillary defect, pupil dilates instead of constricts because of optic nerve defect; named after Scottish ophthalmologist Robert Marcus Gunn. 

===[[Marfan's syndrome]]===
Autosomal dominant, 1/10,000-1/20,000, from mutation in fibrillin-1 gene, associated with long limbs, dislocated lenses, and aortic root dilatation; 50% of children have dilatation of aorta; see also Loeys-Dietz syndrome. 

===Marie's sign===
Fine tremor in hyperthyroidism. 

===Marie-Strümpell disease===
Refers to ankylosing spondylitis in Europe. 

===Marine-Lenhart disease===
Co-existence of TSH-dependent nodules and Graves's disease. 

===Marion's disease===
Congenital obstruction of the posterior urethra. 

===Marjolin's ulcer===
Squamous cell carcinoma ulceration overlying chronic osteomyelitis or burn scar. 

===Markesbery distal myopathy===
Distal myopathy associated with rimmed vacuoles. 

===Markle sign===
Jar tenderness in abdomen from heel drop as a localizing sign of peritoneal irritation; described in 1973. 

===Maroni sign===
Erythema of the skin overlying thyroid in hyperthyroidism. 

===Maroteaux-Lamy syndrome===
Mucopolysaccharidosis (VI) from arylsulfatase B deficiency leading to accumulation of dermatan sulfate characterized by skeletal dysplasia, corneal clouding, coarse facies, valvular heart disease. 

===Marshall syndrome===
Pediatric condition characterized by periodic fever, aphthous stomatitis, pharyngitis, cervical adenitis (PFAPA); origins of syndrome unknown. 

===Marshall syndrome===
Dominantly inherited chondrodysplasias characterized by midfacial hypoplasia, high myopia, and sensorineural hearing deficit, from mutation in COL11A1; similar to Stickler syndrome. 

===Marshall, vein of===
Oblique vein of left atrium. 

===Marshall-Smith syndrome===
Accelerated skeletal maturation, failure to thrive, and dysmorphic facial features with death in early infancy or childhood from pulmonary infections. 

===Martin-Gruber anastomosis===
Anatomic anomaly where there is a branch from the median to ulnar nerve in the forearm, innervating 1st dorsal interosseus, adductor pollicis, and abductor digiti minimi, seen in 10-44% of population. 

===Martin-Lewis agar===
Variant of chocolate agar medium for growing Neisseria. 

===Martorell's ulcer===
Punched out ulcers found on anterior external aspect of leg between middle and lower third of limb. Sharply demarcated, with surrounding halo of erythema, very painful, often crusted, relieved by placing leg in dependent position, . Associated with poorly controlled hypertension. 

===Mary Walker effect===
Effect of physostigmine reversing the effects of myasthenia gravis; described in 1934; Mary Walker, an assistant medical officer at St. Alfege's Hospital in Greenwich England 1920-1936. 

===Masson body===
Granulation tissue plug found in lumen of small airways in bronchiolitis obliterans obstructive pneumonia (BOOP). 

===Mattox maneuver===
For gaining access to the retroperitoneal structures (including aorta), left medium visceral rotation. 

===Matuhasi-Ogata phenomenon===
Non-specific binding of IgG to red blood cells due to the presence of other antibodies binding RBC surface. 

===Maurer's dots===
Seen in P. falcipirum ([[malaria]]) stippling of erythrocytes. 

===Mauriceau-Smellie-Veit maneuver===
In breech delivery, middle finger of one hand is placed in the mouth and thumb on chin to promote flexion and traction, while counter-pressure is applied to the occiput with the other hand. 

===Mayer-Rokitansky-Küster-Hauser syndrome===
Absence of vagina from abnormality of müllerian development. 

===Mayer's reflex===
Basal joint reflex; adduction of the thumb in response to flexion of the metacarpophalngeal joint of the ring finger in a person with a relaxed hand, a normal finding, a normal finding, but may be absent in pyramidal lesions. 

===May-Hegglin anomaly===
Neutrophils with large pale blue inclusions resembling Döhle bodies, giant platelets (30-80 fL v. 7-10 normally), variable thrombocytopenia; rare autosomal dominant asymptomatic trait. 

===Mayne's sign===
In aortic regurgitation, decrease in diastolic pressure of 15 mm Hg when arm is held above the head; of questionable utility since observed in 65% of normal people. 

===Mayo, veins of===
Vein overlying pylorus. 

===May-Thurner syndromne===
Iliofemoral deep vein thrombosis from impaired venous return due to compression of the left common iliac vein by overlying right common iliac artery. 

===Mazzotti reaction===
Reaction to proteins released by dying onchocerca, including fevers, rashes, ocular damage, joint and muscle pain, and lymphangitis as well as hypotension, pyrexia, respiratory distress, and prostration. 

===McArdle's syndrome===
glycogen storage disease V, deficiency in muscle phosphorylase, with consequent glycogen accumulation in skeletal muscle, produces painful muscle cramps and muscle weakness following exercise. 

===McBurney's point===
One-third the distance from the anterior superior iliac spine to the umbilicus. This location corresponds to the most common location of the base of the appendix. 

===McBurney's sign===
In [[appendicitis]], tenderness at McBurney's point. 

===McConnell's sign===
In acute [[pulmonary embolism]], distinct regional pattern of RV dysfunction, with akinesia of the mid-free wall but normal motion at the apex, 77% sensitive, 94% specific for PE. 

===McCune-Albright syndrome===
Triad of irregular café au lait spots, fibrous dysplasia of long bones with cysts, and precocious puberty; from activating mutation in GNAS1 gene. 

===McDonald's sign===
In pregnancy, uterine corpus and cervix can be easily flexed on each other due to Hegar's sign. 

===McGinn-White sign===
S1Q3T3 pattern in pulmonary embolism; described in 1935. 

===McLeod phenotype===
Occurs from the absence of the Kx red blood cell antigen; characterized by acanthocytes; compensated hemolytic anemia; decreased Kell system antigens; increased CKMM isoenzymes; and progressive neurologic changes including areflexia, choreiform movements, dysarthria, wasting of muscles, and cardiomyopathy; may be associated with X-linked chronic granulomatous disease. 

===McMurray test===
For diagnosing meniscal tear, passively flex hip and knee until heel touches buttock, steady the knee with one hand, externally rotate foot, then extend the knee to 90 degrees, return to the beginning and then internally rotate the foot, then passively extend the knee to 90 degrees, feeling for clicks, PPV 83% for tears. 

===McRoberts's maneuver===
Flexion of mother's legs onto abdomen for shoulder dystocia, causing a significant cephalad rotation of the symphysis pubis and subsequent flattening of the sacrum. 

===Means-Lerman scratch===
In hyperdynamic heart (as in hyperthyroidism), a systolic scratch occasionally heard in the second left intercostal space during expiration, presumed to be secondary to rubbing together of normal pleural and pericardial surfaces. 

===Meckel scan===
99Tc pertechnetate scan that selectively tags acid secreting cells (gastric mucosa); it is used most often for unexplained bleeding in infants and young adults. 

===Meckel-Gruber syndrome===
Sloping forehead, posterior encephalocele, polydactyly, and polycystic kidneys. 

===Meckel's cartilage===
Branchial arch 1. 

===Meckel's cave===
Located in skull base, site of trigeminal ganglion and its divisions. Described by Johann Meckel, the Elder; his grandson described Meckel's diverticulum. 

===[[Meckel's diverticulum]]===
Persistence of vitelline duct, contains all 3 layers of bowel (mucosa, submucosa, muscularis propria), antimesenteric, present in 2% of population, usually within 30 cm of ileocecal valve. See also the "five 2s": 2 inches long, 2 feet from ileocecal valve, 2% of population, commonly persists in first 2 years of life, may have 2 types of epithelia. 

===Mediterranean anemia===
Beta thalassemia. 

===Mediterranean fever, familial===
Autosomal recessive disorder characterized by sporadic, paroxysmal attacks of fever and serositis (e.g. abdominal pain). recurrent attacks can be prevented by colchicine. Tends to affect group of people around the Mediterranean Sea. Due to mutation in MEFV gene encoding pyrin. 

===Mediterranean thromboctyopenia===
In Southern Europe, inherited, mild thrombocytopenia with large platelets from mutation in GPIbalpha; genotype and phenotype similar to Bernard-Soulier disease. 

===Mees's lines===
Horizontal white bands of the nails seen in chronic arsenic poisoning, and occasionally in leprosy; usually appears 6 weeks after exposue to arsenic; R. A. Mees, 20th century Dutch physician. 

===Meige's disease===
Lymphedema praecox (in contrast to Milroy's disease). 

===Meige's syndrome===
Blepharospasm with facial dystonia and lip smacking. Described by French neurologist Henri Meige in 1910. 

===Meigs's syndrome===
Unusual combination of hydrothorax, ascites, and ovarian fibroma. 

===Meissner's corpuscle===
Mechanoreceptor in the skin, sensitive to light touch, asymmetrical, lamellated. 

===Meissner's plexus===
Submucous plexus; innervates glandular epithelium, muscularis mucosa, intestinal endocrine cells, and submucosal blood vessels. 

===Meleney's ulcer===
Necrotizing fascitis. 

===Melkersson-Rosenthal syndrome===
Triad of recurrent facial paralysis, recurrent and eventually permanent facial, especially labial edema, and plication of the tongue; etiology unknown; see also Miescher's cheilitis. Onset in childhood or adolescence. 

===Meltzer's triad===
In cryoglobulinemia, triad of palpable purpura, arthralgia and myalgia. 

===Mendelson's syndrome===
Chemical pneumonitis after aspiration of gastric contents. 

===Ménétrier's disease===
Giant cerebriform enlargement of the rugal folds of the gastric mucosa, results from profound hyperplasia of the surface mucous cells with accompanying glandular atrophy, most often encountered in men (3:1), 40s-60s, sometimes in children. May produce epigastric discomfort, weight loss, and sometimes bleeding related to superficial rugal erosions, gastric secretions mostly mucous, little HCl, may cause sufficient protein loss to produce hypoalbuminemia. 

===[[Ménière's disease]]===
Disorder of the inner ear with four classic symptoms: (1) fluctuating sensorineural loss, classically involving low frequencies; (2) vertiginous episodes; (3) aural pressure; (4) tinnitus (frequently roaring); pathologic changes consist of dilation of the endolymphatic system that leads to degeneration of vestibular and cochlear hair cells. 

===Menkes's disease===
X-linked, problem in distribution of copper in the body, amount of copper and ceruloplasmin in serum reduced, excess of copper in intestinal mucosa, muscle, spleen, and kidney, associated with brittle hair; usually fatal by age 3. Believed to be due to defect in copper-transporting-ATPase (ATP7A). 

===Mentzer index===
MCV/RBC ratio; >13 iron def, <13 thalassemia (Lancet 1973 Apr 21;1:882). 

===Merkel cell===
Nerve ending cells located in the skin associated with sensory neurites in the dermal papillae, which are the mechanoreceptors of the skin; speculated to be the cell of origin of Merkel cell carcinoma. 

===Merkel cell carcinoma===
Rare aggressive neuroendocrine tumor involving the skin, predominantly affects elderly Caucasians with a propensity for local recurrence and regional lymph node metastases. 

===Meyer's loop===
A portion of the optic radiations subserving vision from the superior field coursing rostrally within the temporal lobe before heading caudally to the primary visual cortex; lesions produce contralateral upper quadrantanopia (pie in the sky). 

===Meynert, basal nucleus of===
Group of nerve cells in the basal forebrain that are rich in acetylcholine. These cells degenerate in Alzheimer's disease. 

===Mibelli, porokeratosis of===
Classic porokeratosis, localized, chronically progressive, hyperkeratotic, irregular plaques with central atrophy and prominent peripheral keratotic ridge; characterized pathologically by presence of cornoid lamella. 

===Michaelis-Guttmann bodies===
Urinary tract basophilic inclusions. Felt to represent phagosomes mineralized by calcium and iron. Seen in malakoplakia, an inflammatory condition in immunocompromised patients involving urinary tract (rarely skin) with plaques or nodules. 

===Michel deformity===
Congenital absence of the inner ear or labyrinthe aplasia. 

===Middlebrook media===
Medium used for growing mycobacterium. 

===Miescher's cheilitis===
Chelitis granulomatosa; recurrent labial edema on one or both lips; considered a monosymptomatic form of Melkersson-Rosenthal syndrome. 

===Mikulicz's syndrome===
Bilateral inflammatory enlargement of the parotid, submaxillary, and sublingual, and lacrimal glands and xerostomia, secondary to sarcoidosis, leukemia, lymphoma, etc. 

===Milkman's fractures===
In osteomalacia, radiolucent narrow lines that lie either at right angles or obliquely to the cortical outlines of bones and often transect them; bilateral and symmetric, found at the axillary margins of the scapula, lower ribs, neck of the proximal femurs, and posterior regions of the proximal ulnas; related either to stress fractures or to mechanical erosion by penetrating nutrient arteries; also known as Looser's zones. Described by Milkman in 1930. 

===Millard-Gubler syndrome===
Ventral pontine injury causing symptoms similar to Foville's syndrome except lateral rectus weakness only, instead of gaze palsy. 

===Miller Fisher syndrome===
Variant of [[Guillain-Barre syndrome]] where cranial nerves are affected, leading to triad of ataxia, areflexia and ophthalmoplegia; cross-reacting antibodies to GQ1b ganglioside have been found; triggered by certain strains of C. jejuni. Described by neurologist, Charles Miller Fisher. 

===Miller Fisher test===
For testing for [[normal pressure hydrocephalus]], objective gait assessment before and after 30 cc CSF removed, reflecting prognosis for shunting (i.e. improvement after CSF removal). Described by Charles Miller Fisher. 

===Miller syndrome===
Postaxial acrofacial dysostosis, autosomal recessive disorder associated with micrognathia, cleft palate, absent digits, supernumerary nipples, associated with mutation in DHODH.  

===Miller-Moses test===
Water deprivation test for diagnosing diabetes insipidus. 

===Milroy's disease===
Congenital lymphedema with swelling present from time of birth (in contrast to Meige's disease), mainly below the waist, associated with mutation in VEGF C/D receptor (VEGFR-3). 

===Milwaukee brace===
Brace used for treating scoliosis of the back. 

===Milwaukee shoulder===
Basic calcium phosphate disease associated with large joint destructive arthropathy (especially shoulder) and rotator cuff tears. 

===Mirizzi's syndrome===
Extrinsic obstruction of the common bile duct from a cystic duct gallstone. 

===Mississippi mud===
Refers to vancomycin's brownish, muddy appearance in early preparations. 

===Mitchell disease===
Erythromelalgia, or vasodilation and burning pain of lower extremities. Primary erythromelalgia due to mutation in SCN9A, a voltage-gated sodium channel. 

===[[Mittelschmerz]]===
Lower abdominal or pelvic pain during ovulation; occurs roughly halfway of menstrual cycle. From German for "middle pain."

===[[Mobitz Type 1]] AV block===
Wenckebach pattern, second degree block with intermittent conduction failure resulting in progressive PR prolongation before dropped beat; may be seen in ischemic heart disease, digitalis, β-blockers, calcium channel blockers, inferior wall myocardial infarction. 

===[[Mobitz Type 2]] AV block===
Second degree block with intermittent conduction failure with sudden non-conducted sinus P wave without progressive prolongation of PR interval; not seen with digitalis excess or inferior wall myocardial infarction generally but may be seen with anterior wall MI. 

===Möbius syndrome===
Congenital facial paralysis with or without limb defects associated with maternal misoprostol use. 

===Möbius's sign===
In Graves's ophthalmopathy, failure of ocular convergence following close accommodation at a distance of 5 inches. 

===Modigliani syndrome===
Thyroid in normal position, but with enhanced prominence and palpability, especially in individuals with long curving necks. 

===Moersch-Woltmann syndrome===
Stiff-man syndrome; associated with antibodies to glutamic acid decarboxylase (GAD). 

===Mohs's surgery===
Surgery involving microscopic examination of tissue being removed; generally used for skin cancers; developed by Frederic Mohs in the 1930s. 

===Mollaret's meningitis===
Benign recurrent aseptic meningitis characterized by large monocytic cells in CSF; significant percentage due to HSV-2. 

===Mönckeberg's arteriosclerosis===
Ring-like calcifications within the media of medium-sized to small muscular arteries (femoral, tibial, radial, and ulnar arteries, genital arteries), occurs almost exclusively in individuals over 50 years old; does not narrow lumen, distinct from atherosclerosis. 

===Mondini malformation===
Cause of sensorineural hearing loss due to developmental anomaly of otic capsules with developmental arrest of cochlea in seventh fetal week; increased risk of developing recurrent meningitis or perilymphatic fistula. 

===Mondor's disease===
Thrombophlebitis of superficial breast veins. 

===Monge's disease===
Chronic mountain sickness, loss of high altitude tolerance after prolonged exposure, characterized by extreme polycythemia, exaggerated hypoxemia, and reduced mental and physical capacity; relieved by descent. 

===Monod's sign===
In aspergillomas, radiolucent crescent seen around solitary 3-5 cm lesion on chest X-ray. 

===Monro, foramina of===
Connects each of the lateral ventricles with the third ventricle in the brain. 

===Monro-Kellie doctrine===
Cranial cavity is a closed rigid box, change in the amount of intracranial blood can occur only through changes in CSF quantity. 

===Monsel's solution===
Ferric subsulfate, solution used for its styptic properties, i.e. stopping bleeding. 

===[[Monteggia fracture]]===
Fracture of the proximal third of the ulna with a dislocation of radial head. 

===Montgomery, glands of===
Sebaceous glands of areola. 

===Montreal platelet syndrome===
Hereditary thrombocytopenia associated with mucocutaneous bleeding, giant platelets, and spontaneous platelet clumping in vitro; associated with type 2B VWD and the V1316M mutation. 

===Mooren corneal ulcers===
Chronic, painful ulcers, involves circumference of peripheral cornea and may progress to vision loss. Most cases are idiopathic, some are associated with hepatitis C. 

===Morgagni, hydatids of===
Fallopian tube cysts found near the fimbriated end or in the broad ligaments. 

===Morgagni's hernia===
A form of congenital diaphragmatic hernia, anterior parasternal diaphragmatic hernia, right more common than left. Compare to Bochdalek hernia. 

===Morquio's syndrome===
Mucopolysaccharidosis (IV) from N-acetylglucosamine-6-sulfate sulfatase deficiency leading to accumulation of keratan sulfate and chondroitin-6 sulfate, characterized by distinctive skeletal deformity, corneal clouding, odontoid hypoplasia, and aortic valve disease. Normal intelligence. 

===Morrison's pouch===
Hepatorenal recess; the most posterior cavity in the peritoneal cavity. 

===Morton's neuroma===
Interdigitial palmar neuroma. 

===Morvan's syndrome===
Fibrillary chorea; neuromyotonia, pain, weight loss, severe insomnia and hallucinations, excess secretions (sweating, lacrimation, and salivation); associated with voltage-gated potassium channel antibodies. 

===Moschowitz syndrome===
Thrombotic thrombocytopenic purpura, described in 1924. 

===Moses's sign===
See Bancroft's sign. 

===Mott cells===
Cytologic variant of plasma cells with globular cytoplasmic inclusions that contain immunoglobulin proteins (blue, grapelike cytoplasmic droplets); seen in multiple myeloma and trypanosomiasis. 

===Mounier-Kuhn syndrome===
Tracheomegaly, tracheobronchomegaly associated with recurrent pneumonia, copious purulent sputum production, hoarseness, load cough; presents in 30s-40s, more common in males; tracheal lumen increases with Valsalva; autosomal recessive. 

===[[Moyamoya]] disease===
Occlusive disease involving large intracranial arteries, especially the distal ICA and stem of the MCA and ACA; "puff of smoke" (in Japanese, moya moya) appearance on angiography from lenticulostriate arteries developing rich collateral circulation around the middle cerebral occlusion that; anticoagulation challenging because of occurrence of SAH from rupture of the transdural anastomotic channels.

===Mucha-Habermann disease===
Pityriasis lichenoides et varioliformis acuta, scattered necrotic papules and vesicles that can resemble insect bites but usually are more generalized and symmetric. Felt to be a form of a self-limited lymphoproliferative disease. 

===Muckle-Wells syndrome===
Syndrome of urticaria, progressive perceptive deafness, and amyloidosis; from mutation in cryopyrin; autosomal dominant. Of note familial cold autoinflammatory syndrome, commonly known as familial cold urticaria, characterized by intermittent episodes of rash, arthralgia, fever and conjunctivitis after generalized exposure to cold is also associated with mutations in cryopyrin. 

===Muehrcke's nails===
Paired narrow horizontal white bands that are immobile as nail grows; seen in hypoalbuminemia, nephrotic syndrome. 

===Muenke syndrome===
Nonsyndromic coronal craniosynostosis, associated with a specific mutation of the fibroblast growth factor receptor-3 gene (FGFR3), Pro250 to Arg. 

===Muir-Torre syndrome===
Combination of hereditary nonpolyposis colon cancer (HNPCC) with benign or malignant sebaceous skin tumors (often basal cell or squamous cell). Originally described in 1967. 

===Mulder's sign===
Palpable click in Morton's neuroma when compressing the forefoot and pushing up in the distal third intermetatarsal space. 

===Mullerian duct===
In female embryonic development, duct that gives rise to fallopian tubes, uterus, and upper vagina. 

===Mullerian inhibiting substance===
In embryonic development, gonadal peptide hormone that initiates regression of Mullerian duct during male sexual development. 

===Müller-Lyer illusion===
Visual illusion involving two horizontal lines with arrows where line with inward facing arrows appears shorter than line with outward facing arrows. 

===Müller's maneuver===
Reverse Valsalva maneuver. 

===Müller's sign===
In aortic regurgitation, systolic pulsations of the uvula. 

===Munchausen's syndrome===
[[Factitious disorder]], eponym given by Asher in 1951 after Baron Karl Munchausen (1720-1797), retired German cavalry officer with a reputation for preposterous stories about his activities as a soldier, hunter. 

===Munro's microabscesses===
In psoriasis, when neutrophils form small aggregates within the parakeratotic stratum corneum. 

===Murphy drip===
Saline infusion in the rectum for treating peritonitis; also refers to continuous irrigation of the bladder; after John Benjmain Murphy surgeon (1896-1982) of Murphy's sign. 

===Murphy eye===
Small hole in the side of the endotracheal tube that allows for ventilation if the distal end becomes occluded. 

===Murphy's punch sign===
Tenderness over costovertebral angle suggesting [[pyelonephritis]]. 

===Murphy's sign===
A sharp increase in tenderness with a sudden stop in inspiratory effort, sign of acute [[cholecystitis]]; 27-97.2% sensitive, 48.3% specific. 

===Mustard procedure===
For treating transposition of great vessels, now rarely used; an atrial inversion procedure which connects RA to LV, which pumps out to pulmonary arteries, and connects LA to RV, which becomes systemic pump to aorta; variant uses pericardial or prosthetic intraatrial baffles. 

===Myerson's sign===
Repetitive tapping (about twice per second) over the bridge of the nose producing a sustained blink response in parkinsonism and as a frontal release sign; also known as glabellar reflex. Normal response is to resist blinking.

==N==

===Naclerio, V sign of===
In [[esophageal rupture]], V-shaped collection of air along mediastinum and diaphragm. 

===Nagayama spots===
In [[roseola]], erythematous papules on the soft palate and uvula. 

===Nägele's rule===
Method for estimating date of delivery by counting back 3 months from the first day of the last menstrual period and adding seven days; full term 38 weeks after fertilization, 40 weeks after last menstrual period. 

===Nardi test===
In relapsing pancreatitis, narcotic-induced stimulation or spasm reproducing abdominal pain and amylase elevation (for inferring sphincteric disease in any pancreatic or biliary ductal system without a gallbladder), presumably accurate in the diagnosis of perisphincteric disease. 

===Natowicz syndrome===
Mucopolysaccharidosis type IX, from hyaluronidase deficiency. Characterized by short stature and multiple soft tissue masses around joints. Described by Natowicz in 1996. 

===Naxos disease===
Initially described on Greek island of Naxos, syndrome of arrhythmogenic right ventricular cardiomyopathy, non-epidermolytic palmoplantar keratoderma, and woolly hair, due to deletion in plakoglobin, protein in adherens and desmosomal junctions. 

===Neer sign===
In shoulder impingement, forcibly flexing the arm to an overhead position to produce pain from impingement of humerus against coracoacromial arch. 

===Negri bodies===
In [[rabies]] virus-infected brain neurons, eosinophilic cytoplasmic inclusions. 

===Nelson's syndrome===
Enlargement of a pituitary adenoma in a patient with Cushing's disease whose adrenals have been removed; from loss of feedback inhibition of cortisol. 

===Neu-Laxova syndrome===
Autosomal recessive syndrome characterized by severe intrauterine growth retardation, microcephaly, abnormal brain development, edema, and icthyosis. First reported in 1971 by Neu et al. (Pediatrics 47;610-612). 

===Nezelof syndrome===
Congenital immunodeficiency syndrome, autosomal recessive, due to thymic dysplasia. 

===Nicolau's syndrome===
Livedo-like dermatitis from acute arterial thrombosis occurring immediately after intravascular injection of an insoluble drug substance. 

===Niemann-Pick disease===
A sphingolipidosis where there is lysosomal accumulation of sphingomyelin and cholesterol, type A and B (deficiency of sphingomyelin-cleaving enzyme sphingomyelinase) and type C and D (enzyme normal or nearly normal, defect in esterification and transport); type A, 75-80% of all cases, extensive neurologic involvement, marked visceral accumulations of sphingomyelin, and progressive wasting and early death within the first 3 years of life); half have cherry red spot in macula as in Tay-Sachs disease. 

===Niikawa-Kuroki syndrome===
See kabuki syndrome. 

===Nijmegen breakage syndrome===
Primary immunodeficiency autosomal recessive disorder that presents as microcephaly, a distinctive "bird-like" facies, growth retardation, recurrent pulmonary infections, chromosomal instability, radiation hypersensitivity, and increased incidence of malignancies, especially lymphomas from mutation in nibrin protein, a protein involved in DNA repair; cellular defect similar to ataxia-telangiectasia. 

===Nikaidoh procedure===
Procedure for patients born with a combination of transposition of the great arteries, ventricular septal defect, and pulmonary stenosis. In contrast with the Rastelli procedure, the Nikaidoh procedure creates a more "anatomically correct" left ventricular outflow tract. Also known as aortic translocation and biventricular outflow tract reconstruction. 

===Nikolsky's sign===
Nikolsky sign is a skin finding in which the top layers of the skin slip away from the lower layers when rubbed (i.e., when lateral pressure is applied on the border of an intact blister, which results in the dislodgment of the normal epidermis and extension of the blister).<ref>Maity S, et al. "Nikolsky's sign: A pathognomic boon." J Family Med Prim Care. 2020 Feb; 9(2): 526–530. Published online 2020 Feb 28. doi: 10.4103/jfmpc.jfmpc_889_19. PMCID: PMC7114071. PMID: 32318376</ref> This occurs when apparently normal epidermis next to blister may be separated at the basal layer and rubbed off when pressed with a sliding motion. It is classically associated with [[pemphigus vulgaris]] and [[toxic epidermal necrolysis]], but may have other causes. See also Asboe-Hansen sign.

===Nissen fundoplication===
For treating [[gastroesophageal reflux disease]], surrounding lower end of esophagus with cuff of gastric fundal muscle to increase lower esophageal sphincter competence. 

===Nissl bodies===
In neurons, rough endoplasmic reticulum. 

===Nissl stain===
Stains for cell bodies; dye binds to acid groups, in particular the RNAs of the ribosomes located within the cell body. Described by Franz Nissl, German medical student at time. 

===Noonan's syndrome===
Turner's phenotypic characteristics without any sex chromosome abnormalities, males or females with congenital heart defect (usually pulmonic stenosis and hypertrophic cardiomyopathy), pectus carinatum, short stature, mild mental retardation, hypertelorism, and webbed neck; autosomal dominant; associated with mutation in nonreceptor protein tyrosine phosphatase SHP2 (PTPN11). Most common non-chromosomal cause of congenital heart disease. 

===Norman-Landing disease===
GM1 gangliosidosis, a lysosomal storage disorder. 

===Norrie disease===
X-linked disorder associated with very early childhood blindness due to degenerative changes of the retina; associated with mental retardation and psychotic-like features; due to mutation in gene encoding norrin. 

===Norwalk virus===
[[Norovirus]]; calcivirus associated with gastroenteritis; named after outbreak in a school in Norwalk, Ohio in 1969. 

===Norwegian scabies===
Crusted scabies, highly contagious, psoriaform dermatosis of the hands and feet with dystrophy of the nails and an erythematous scaling eruption that may be generalized; itching minimal; seen in institutionalized patients, mentally retarded, and in patients with HIV, HTLV-1, or adult T cell leukemia. Initially described in Norwegian patients with leprosy in 1840s. 

===Norwood procedure===
For treating [[hypoplastic left heart syndrome]], anastomosis of proximal main pulmonary artery to aorta, with aortic arch reconstruction and transection and patch closure of distal main pulmonary artery; modified right Blalock-Taussig shunt (subclavian artery to right PA) to provide pulmonary blood flow. ASD created to allow for adequate left to right flow. See also Glenn shunt and Fontan procedure as subsequent stages. 

===Nothnagel's syndrome===
Injury to superior cerebellar peduncle causing ipsilateral oculomotor palsy and contralateral cerebellar ataxia. 

==O==

===Ober's test===
Provocative test for iliotibial band syndrome: patient lies on unaffected side and affected leg is abducted while knee is flexed to 90 degrees and leg is then released; positive for iliotibial band syndrome when thigh is released and thigh remains abducted. 

===Occam's razor===
Described in 14th century, "plurality must not be posited without necessity", in other words, parsimony in diagnosis; by contrast, see Hickam's dictum. 

===Oddi, sphincter of===
Sphincter around opening of common bile duct into the duodenum; Oddi, Italian anatomist and surgeon (1864-1913). 

===[[Ogilvie's syndrome]]===
Massive idiopathic non-obstructive dilatation of the colon, can be sen in ill patients. 

===Oguchi disease===
Congenital night blindness; asymptomatic during day; found to be due to mutations in arrestin (in Japanese Oguchi disease) and rhodopsin kinase (in European Oguchi disease). 

===Ohtahara syndrome===
Early infantile epileptic encephalopathy with burst-suppression. EEG shows high voltage spike wave discharge followed by burst suppression. Assocated with death in childhood or progression into West's syndrome and Lennox-Gestaut syndrome. Ivan Cameron, son of David Cameron (UK prime minister) , died of this condition. 

===Okihiro syndrome===
Association of forearm malformations with Duane syndrome of eye retraction; associated with mutations in SALL4. 

===Oliver's sign===
In aortic aneurysm, pulsation of aorta felt through cricoid cartilage when chin is elevated. 

===Ollendorf's sign===
Tender papule in secondary syphilis. 

===Ollier's disease===
Syndrome of multiple enchondromas. Increased risk of sarcoma. No known genetic component. 

===Omenn's syndrome===
Combined immunodeficiency associated with hypereosinophilia, erythroderma, hepatosplenomegaly, lymphadenopathy, alopecia; autosomal recessive; associated with mutations in Rag-1 and Rag-2 proteins and decreased V(D)J recombination efficiency. Also associated with mutation in ARTEMIS protein (involved in opening coding end hairpins). 

===Ommaya reservoir===
Device implanted under the scalp that communicates with the CSF and allows intrathecal delivery of therapeutic agents (e.g., chemotherapy). 

===Ondine's curse===
Failure of the automatic control of ventilation, named after mythological tale in which the suitor of Neptune's daughter was cursed to lose automatic control over all bodily functions; associated with mutation in ret proto-oncogene; associated with Hirschsprung's disease. 

===Onufrowicz, nucleus of===
Parasympathetic neurons in the sacral spinal cord that innervate the sphincters of the bowel and bladder. 

===Opitz syndrome===
Also known as Opitz GBBB syndrome. Hypospadias-dysphagia syndrome or telecanthus with associated abnormalities; associated with midline abnormalities such as cleft lip, laryngeal cleft, heart defects, hypospadias, and agenesis of the corpus callosum. 

===Oppenheim's sign===
Involuntary dorsiflexion of the toes when stroking the medial/anterior tibial surface superiorly to inferiorly, indicating upper motor neuron defect. 

===Ormond's disease===
Retroperitoneal fibrosis. 

===Oroya fever===
From Bartonella bacilliformis (transmitted by sandfly vector Phlebotomus found in valleys of the Andes mountains, 600-2500 m): profound intravascular hemolytic anemia of a few weeks duration, associated with lesions called verruga peruana resembling Kaposi's sarcoma; also known as Carrión's disease. 

===Ortner's syndrome===
Hoarseness from compression of left recurrent laryngeal nerve by a dilated left atrium (e.g., in mitral stenosis), enlarged tracheobronchial lymph nodes, and dilated pulmonary artery. 

===Ortolani's sign===
In congenital hip dislocation, rotate hip with patient in supine position and hip abducted; a "clunk" or "click" represents congenitally dislocated hip. 

===Osborn wave===
ECG with distinctive convex "hump" at J point associated with [[hypothermia]] and temperature around 32C. 

===[[Osgood-Schlatter disease]]===
Epiphysitis of tibial tubercle resulting from repeated powerful contractions of the quadriceps; seen in adolescents with open physis. 

===Osler's nodes===
In [[endocarditis]], tender to painful, purplish, split pea-sized, subcutaneous nodules in the pulp of the fingers and/or toes and thenar and hypothenar eminences; transient, disappearing within several days (5% of patients). In acute bacterial endocarditis, associated with minute infective emboli. In subacute bacterial endocarditis, associated with immune complexes and small-vessel arteritis of skin. 

===Osler's sign===
Palpable brachial or radial artery when cuff pressure greater than systolic pressure. 

===Osler-Weber-Rendu disease===
Hereditary hemorrhagic telangiectasia, larger lesions can be a source of chronic blood loss, systemic emboli, hypoxemia, hepatic dysfunction, and a high-output cardiac failure. Important risk factor for brain abscess, especially in affected patients with clubbing, cyanosis, and/or polycythemia. Can be treated with aminocaproic acid (an antifibrinolytic agent. 

===Ota, nevus of===
Pigmentation mostly involving the skin and mucous membranes innervated by the first and second branches of the trigeminal nerve. 

===Ottawa ankle rules===
Decision guide for managing acute ankle injury and ordering ankle and foot x-ray series. Ankle x-ray series required only if there is any pain in the malleolar zone and any of these findings: bony tenderness at posterior edge or tip of lateral malleolus, base of fifth metatarsal, or inability to bear weight both immediately and in emergency department. Foot x-ray is required only if there is any pain in the midfoot zone and any of these findings: bone tenderness at base of fifth metatarsal, bone tenderness at navicular, or inability to bear weight both immediately and in emergency department. 

===Ouchterlony reaction===
Test based on the precipitin reaction where antigen and antibody are placed in separate wells cut in agar; precipitate forms a band between wells at the optimal concentration; described by Ouchterlony in 1948.

===Owren's disease===
Factor V deficiency; also known as parahemophilia. 

==P==

===Pacinian corpuscles===
Mechanoreceptor nerve ending located in skin, sensitive for vibration and touch; symmetrical, lamellated. 

===[[Paget disease]] of bone===
Osteitis deformans, characterized by initial osteolytic stage followed by a mixed osteoclastic-osteoblastic stage, which ends with osteoblastic activity and evolves into a burnt-out osteosclerotic stage. Increased alkaline phosphatase and increased urine hydroxyproline observed.

===Paget's disease of breast===
Breast cancer involving nipple and areola, appears as eczematous rash over breast with crusting, scaling, or erosion. 

===Paget's disease of vulva===
Intraepithelial adenocarcinoma, less than 1% of all vulva malignancies. 

===[[Paget-Schroetter syndrome]]===
Deep vein thrombosis of subclavian or axillary vein. May be spontaneous or may occur after activity. 

===Palla's sign===
In pulmonary embolism, enlarged right descending pulmonary artery. 

===Pallister-Hall syndrome===
Disorder associated with polydactyly and cutaneous syndactyly. Hypothalamic hamartoma characteristic, bifid epiglottis. Autosomal dominant, due to mutation in GLI3, involved in hedgehog pathway. See also Greig syndrome, which is also due to mutation in GLI3. 

===Panayiotopoulos syndrome===
Benign childhood partial seizure characterized by vomiting, deviation of the eyes, and seizures lasting for more than 30 min (without permanent injury). 

===[[Pancoast Syndrome|Pancoast's tumor]]===
Apical lung cancers in the superior pulmonary sulcus which invade neural structures around the trachea, including the cervical sympathetic plexus, leading to severe pain in distribution of the ulnar nerve and Horner's syndrome on same side of the lesion.

===Paneth cells===
In small intestine crypts, cells with apically-oriented bright eosinophilic granules and which appear to play a role in the mucosal immune system. 

===Panner disease===
Avascular necrosis or osteochondrosis of the capitellum (head of humerus). 

===Panton-Valentine leukocidin===
Cytotoxin associated with increased virulence of Staph. aureus (especially community-acquired MRSA) and involved in pathogenesis of necrotic lesions and necrotizing pneumonia. 

===Pap smear===
Smear of cervical cells developed by Papanicolaou, reported in 1941, used for screening and prevention of cervical cancer. 

===Papez circuit===
Pathway from subiculum to the mamillary body and back to the cingulate gyrus believed to play a role in emotion (initially) and memory. 

===Papillon-Lefevre disease===
Early development of severe periodontal disease, palmoplantar keratosis; autosomal recessive; associated with mutation in cathepsin C gene. 

===Pappenheimer bodies===
Small dark blue irregularly shaped iron-containing granules often in clusters found in red blood cells. Smaller than Howell-Jolly body, commonly seen in sideroblastic anemias, thalassemias, megaloblastic anemias, and in post-splenectomy states. 

===Pardee waves===
Symmetrically inverted T waves in myocardial ischemia or infarction. 

===Parinaud's oculoglandular syndrome===
Preauricular node enlargement associated with chronic granulomatous conjunctivitis; an atypical form of cat scratch disease from inoculation near eye. 

===Parinaud's syndrome===
Dorsal midbrain syndrome with supranuclear vertical gaze disorder from damage to posterior commissure with loss of upgaze, convergence-retraction nystagmus, downward ocular deviation, lid retraction, due to hydrocephalus from aqueductal stenosis, pineal region tumors. 

===Paris-Trousseau syndrome===
A variant of Jacobsen's disease, mild hemorrhagic tendency associated with 11q deletion, thrombocytopenia, attributed to deletion of FLI1. 

===[[Parkinson's disease]]===
Degenerative disorder of central nervous system due to degeneration of dopaminergic neurons of the substantia nigra which project to the striatum; characterized by tremor, rigidity, akinesia, and gait disturbance. Described by James Parkinson in 1817. 

===[[Parkland formula]]===
For calculating amount of intravenous fluids to give in burn patients: total body surface area % burned x kg x 4; 1/2 in first 8 hours, second 1/2 given next 16 hours. 

===Parry-Romberg syndrome===
Acquired progressive hemifacial atrophy of the lower face, typically without significant cutaneous involvement; a variant of morphea/scleroderma. 

===Parsonage-Turner syndrome===
Acute brachial neuritis or neuralgic amyotrophy; classically severe pain followed by weakness in the brachial plexus, associated with winging of the scapula. 

===Passy-Muir valve===
Speaking valve for patients with tracheostomy developed by Patricia Passy and David Muir. 

===Pastia's sign===
Associated with scarlet fever (group A streptococcus or S. aureus rarely); confluent, finely punctate erythema (scarlatiniform) on the lower trunk and thighs with petechiae having a linear configuration in the inguinal regions . 

===Patau's syndrome===
Trisomy 13, 1/15,000 births, mental retardation, microcephaly, microphthalmia, brain abnormalities, cleft lip and palate, polydactyly, rocker-bottom feet, and congenital heart disease. Extra chromosome 13 described by Klaus Patau in 1960. 

===Patrick sign===
Hip pain on external rotation of the hip in hip joint disease that may refer pain to back and thighs. 

===Patterson-Brown-Kelly syndrome===
Plummer-Vinson syndrome. 

===Paul-Bunnell test===
Agglutination of sheep red blood cells by heterophile antibodies. 

===Paul-Bunnell-Davidsohn test===
Extension of classic Paul-Bunnell test for heterophile antibody; uses guinea pig kidney cells to first absorb Forsmann antibodies found in normal individuals, followed by test for sheep erythrocyte agglutination. 

===Pautrier's microabscesses===
See Sézary-Lutzner cells. 

===Pearson syndrome===
Refractory sideroblastic anemia with vacuolization of marrow precursors and exocrine pancreatic dysfunction from mitochondrial DNA mutation. 

===Pedro Pons sign===
In spondylitis from brucellosis, erosion antero-superior corner of lumbar vertebrae and marked osteophytosis. 

===Pel-Ebstein fever===
In [[Hodgkin's lymphoma]], unusual systemic manifestation of a periodic fever that is present for some days, remits, and then returns. 

===Pelger-Hüet anomaly===
Dumbbell-shaped, hypolobated nuclei in neutrophils seen in blood of acute myelogenous leukemia (e.g., M2) or myelodysplastic syndromes. May be inherited as autosomal dominant trait from mutation in laminin B receptor. 

===Pelizaeus-Merzbacher disease===
Mutation in proteolipid protein on X chromosome, a major protein in CNS myelin; results in hypomyelination confined to the CNS, widespread white matter dysfunction, leading to seizures, mental retardation, and death in childhood; see "tigroid" appearance on tissue sections stained for myelin. 

===Pellegrini-Stieda syndrome===
Calcification of medial collateral ligament at its femoral insertion; usually due to trauma. 

===Pemberton's sign===
In [[SVC obstruction]], development of facial plethora, inspiratory stridor, and non-pulsatile elevation of the JVP when patient lifts arms over head. 

===Pendred's syndrome===
Autosomal recessive goiter and congenital sensorineural deafness from mutation in pendrin, a transport protein that affects organification of thyroglobulin; also see malformations of cochlea and hypothyroidism (40%); pendrin involved in transport of chloride and iodide. 

===Percheron, artery of===
Anatomic variant where artery arises from posterior communicating artery and then gives rise to bilateral medial thalamic perforators; occlusion results in bilateral paramedian thalamic infraction. An example where cerebral vessel supplies structures on both sides of the midline. 

===Perlia's nucleus===
Cell group located between motor neuron groups innervating left and right medical rectus muscles; felt to be involved in ocular convergence. 

===Perl's stain===
Stain for iron; tissue section treated with hydrochloric acid to release ferric ions from binding proteins; section then treated with potassium ferrocyanide to produce an insoluble blue compound (the Prussian blue reaction). 

===Perthes syndrome===
Traumatic asphyxia from [[crush injury]] to the chest, associated with petechiae in chest, subconjuctival hemorrhage. 

===Perthes test===
Testing for competence of deep femoral veins; tourniquet is applied at mid-thigh with patient standing and patient then walks for 5 min with tourniquet pin place; reduction in size of veins indicates patent valves and lumens. 

===Petersen's hernia===
Hernia involving the space between the mesentery of the Roux limb and the transverse colon; can occur following gastric bypass surgery. 

===Peutz-Jeghers syndrome===
Rare autosomal dominant syndrome characterized by multiple hamartomatous polyps scattered throughout the GI tract and melanotic mucosal and cutaneous pigmentation around the lips, oral mucosa, face, genitalia, and palmar surfaces; patients have increased risk of carcinomas of pancreas, breast, lung, ovary, uterus, and malignant transformation in small bowel polyps, colon cancer, sex cord tumors with annular tubules of the ovary; associated with mutation in STK11/LKB1 gene and dysregulation of mTOR. 

===Peyrone's salt===
Cisplatin; first synthesized by Peyrone in 1845. 

===Peyronie's disease===
Penile fibromatosis, a palpable induration or mass appears on the dorsolateral aspect of the penis. It may cause eventually abnormal curvature of the shaft or constriction of the urethra, or both. 

===Pfannenstiel's incision===
Low transverse abdominal incision with retraction of the rectus muscles laterally, used in ob/gyn procedures. 

===Pfeiffer bacterium===
H. influenza, found in respiratory tracts of people ill with flu in 1890. 

===Pfeiffer syndrome===
Craniosynostoses as well as limb defects, broad thumbs, broad great toes. Due to mutations in FGFR1, autosomal dominant inheritance. 

===Phalen's maneuver===
In [[carpal tunnel syndrome]], palmar flexion of the wrist to 90 degrees for 1 minute exacerbates or reproduces symptoms, paresthesias; 75% sensitive 47% specific. 

===Phemister's triad===
In arthritis from tuberculosis, radiographic triad of periarticular osteoporosis, peripherally located osseous erosions, and gradual narrowing of the joint space. 

===Philadelphia chromosome===
Seen in 95% of [[chronic myelogenous leukemia]] (210 kD tyrosine kinase), 2-5% childhood ALL (180 kD TK), higher percent in adult. Reciprocal and balanced translocation between chr22 (bcr, breakpoint cluster region) and chr9 (c-abl); c-abl-bcr encodes a chimeric protein with tyrosine kinase activity; genomic imprinting, chr9 paternal and chr22 maternal. 

===Pick bodies===
In neurons, cytoplasmic, round to oval, filamentous inclusions that strongly stain with silver, weakly eosinophilic; composed of neurofilaments, vesiculated endoplasmic reticulum, and paired helical filaments that are immunocytochemically similar to those found in Alzheimer's disease. Associated with Pick's disease. 

===Pick cells===
Characteristic swelling of neurons in Pick's disease. 

===Pick's disease===
Subtype of frontal lobe dementia, characterized by language abnormalities such as logorrhea, echolalia, and palilalia (compulsive repetition of phrases), with Pick bodies; occurs 1-5% as often as Alzheimer's disease. 

===Pickwickian syndrome===
Obesity hypoventilation syndrome defined by extreme obesity and alveolar hypoventilation during wakefulness, characterized by hypersomnolence, dyspnea, hypoxemia (cyanosis, polycythemia, and plethora), and pulmonary hypertension leading to RV failure and edema; based upon Charles Dickens' book The Posthumous Papers of the Pickwick Club and the character Joe who was a "wonderfully fat boy, standing upright with his eyes closed." 

===Pierre Robin syndrome===
Micrognathia and abnormal smallness of the tongue, often with cleft palate, severe myopia, congenital glaucoma, and retinal detachment; described by French dental surgeon Pierre Robin, 1867-1950. 

===Pink disease===
Acrodynia, occurs from exposure to high concentrations of mercury vapor, characterized by a body rash, swelling and irritation of palms and feet followed by skin desquamation, irritability, photophobia, fever, insomnia and profuse sweating. May also follow oral exposure to mercury compounds. 

===Piper forceps===
Forceps with a perineal curve to facilitate breech delivery. 

===Pisa syndrome===
Pleurothotonus, rare side-effect of classic neuroleptic medication, characterized by dystonia with flexion of body and head to one side and axial rotation of the trunk; has been seen in cholinesterase inhibitors as well; originally described in 1972. After leaning tower of Pisa. 

===Piskacek's sign===
Early sign of pregnancy where there is asymmetry of the uterus with a well-defined soft prominence of the cornu, due to implantation near one of the cornua; also known as von Braun-Fernwald's sign. 

===Pittsburgh pneumonia agent===
[[Legionella]] micdadei. 

===Plummer's disease===
Toxic multinodular goiter. 

===Plummer's nail===
Onycholysis as a sign of hyperthyroidism, especially when it affects the ring finger. 

===Plummer-Vinson syndrome===
Classic triad of dysphagia, iron deficiency anemia, and esophageal webs. Associated with atrophic glossitis and koilonychia. Associated with increased risk of squamous cell cancer of the pharynx and esophagus. Also known as Patterson-Brown-Kelly syndrome. 

===Pohl-Pinkus constriction===
Along hair shaft, area of decreased diameter, usually due to systemic stress, e.g. from chemotherapy, resulting in vulnerability to breaks. First described by Pohl in 1894, who later apparently changed his name to Pinkus. See also Beau's lines. 

===Poiseuille's law===
Flow proportional to fourth power of radius, inversely proportional to length. 

===Poland syndrome===
Amastia associated with hypoplasia of ipsilateral musculature (microsyndactyly or lack of one hand) and chest wall (atrophy of the ipsilateral pectoralis major) and GU abnormalities; 10% have dextrocardia or dextroversion. 

===Polle syndrome===
Munchausen's syndrome by proxy; after daughter Polle from second marriage of Munchausen to 17 y.o. Bernhardine at age 74, daughter died 1 year later (though paternity apparently suspect) (Lancet 1977;2:456); but daughter Polle apparently does not exist but name of town where Bernhardine came from (Pediatrics 1984;74:554). 

===Pompe's disease===
Type II glycogen storage disease, deficiency in alpha-1,4-glucosidase (lysosomal enzyme) with consequent accumulation of glycogen, especially in the liver, heart, and skeletal muscle, characterized by cardiomegaly, muscle hypotonia, and splenomegaly, death from cardiorespiratory failure before age 3. 

===Poncet's disease===
In acute [[tuberculosis]] infection, aseptic inflammatory polyarthritis. 

===Pontiac fever===
Nonpneumonic legionellosis. Named after July 1968 outbreak in Pontiac, Michigan. 

===Porter-Silber test===
Measurement of urinary 17-OH corticosteroid. 

===Posner-Schlossman syndrome===
Glaucomatocyclitic crisis; recurrent episodes of markedly elevated intraocular pressure with mild idiopathic anterior chamber inflammation. 

===Potocki-Lupski syndrome===
Syndrome characterized by mild mental retardation, attention-deficit, hyperactivity, and autism, short stature, and dental abnormalities such as malocclusion and crowded teeth. Associated with duplication of 17p11.2. Compare with Smith-Magenis syndrome, which is associated with deletino of 17p11.2. 

===Potter's sequence===
From oligohydramnios (from e.g. renal agenesis, amniotic leak) leading to amnion nodosum, fetal compression which leads to pulmonary hypoplasia, altered facies, positioning defects of feet, hands, and breech presentation. 

===Pott's disease===
Involvement of the spine with tuberculosis; occurs in about 2% of TB cases. 

===Pott's fracture===
Fracture of distal fibula. 

===Pott's puffy tumors===
Extension of frontal sinusitis anteriorly into frontal bone causing a distinct swelling. 

===Potts shunt===
For treating [[tetralogy of Fallot]], anastomosis of direct descending aorta to left pulmonary artery; now rarely performed. 

===Poupart's ligament===
Inguinal ligament. 

===Prader-Willi syndrome===
Deletion of 15q11-q13 with paternal imprinting. Characterized by uncontrollable hyperphagia after 12 months, associated with short stature, hypogonadism, and mild mental retardation. 

===Pratt's sign===
In deep vein thrombosis, presence of three dilated veins or sentinel veins over the tibia; dilatation persists when legs are elevated to 45 degrees. 

===Prausnitz-Küstner reaction===
Passive transfer of cutaneous anaphylaxis; transferring serum of affected patient intradermally into a recipient and then challenging recipient with antigen 24 hours later at the same site and checking for wheal and flare; known since 1920s. 

===Prehn's sign===
Elevation of painful testicle decreases pain of epididymitis. 

===Preiser disease===
Spontaneous, non-traumatic osteonecrosis of the scaphoid bone.

===Pregerson's Sign===
Subpatellar bulge with knees flexed; associated with Knee effusion

===Pringle maneuver===
Clamping of porta hepatis to control hemorrhage. 

===[[Prinzmetal's angina]]===
Variant angina occurring at rest, manifesting on ECG as episodic ST segment elevations, caused by coronary artery spasms with or without superimposed coronary artery disease; patients more likely to develop ventricular arrhythmias. 

===Probst bundle===
Callosal longitudinal bundle, seen in agenesis of the corpus callosum from fibers from the hemispheres failing to cross the midline and instead forming thick bundles. 

===Proteus syndrome===
Congenital condition characterized by generalized, unilateral, or localized overgrowth of any tissue type, hemihypertrophy, lymphangiomas, lipomas, hemangiomata macrocephaly; thought that Joseph Merrick, the "Elephant Man" may have had this condition rather than neurofibromatosis; associated with mutation in PTEN. Named after Greek sea-god, Proteus, who could change his appearance. 

===Psammoma bodies===
Round collection of calcium seen in papillary thyroid cancer, renal cell carcinoma, etc.; from the Greek for "sand."

===Psoas Sign===
Pain elicited by extending the hip with the knee in full extension, seen with appendicitis and psoas inflammation.

===Puestow procedure===
For chronic pancreatitis, side-to-side anastomosis of the pancreas and jejunum for decompressing dilated main pancreatic duct and providing pain relief. 

===Pulfrich phenomenon===
Misperception of trajectory of moving objects (an optical illusion that can be elicited in normal subjects), can be associated with optic neuritis. 

===Purkinje cells===
Neurons in the cerebellar cortex that secrete GABA; some of the largest cells in the brain. 

===Purtilo's syndrome===
X-linked lymphoproliferative syndrome, more commonly known as Duncan's disease. 

===Purtscher's angiopathic retinopathy===
In acute pancreatitis, sudden and severe loss of vision due to posterior retinal artery occlusion with aggregated granulocytes; discrete flame-shaped hemorrhages with cotton-wool spots; also seen in fat embolization. First described in 1919 by Othmar Purtscher. 

===Pyle's disease===
Metaphyseal dysplasia, few clinical associations other than genu valgum despite bizarre radiographic findings (e.g. marked thickening of ribs, clavicles, Erlenmeyer flask-like flare of femur). Autosomal recessive.


==See Also==
*[[Eponyms (A-B)]]
*[[Eponyms (C-E)]]
*[[Eponyms (M-P)]]
*[[Eponyms (Q-S)]]
*[[Eponyms (T-Z)]]

==References==
<references/>
[[Category:Misc/General]]