Fanconi anemia

Fanconi anemia (FA) is the most common inherited bone marrow failure syndrome, characterized by progressive pancytopenia, congenital anomalies, and markedly increased cancer susceptibility. Emergency physicians encounter FA patients presenting with hemorrhagic emergencies, febrile neutropenia, severe anemia, and malignancy complications. Critically, FA patients have extreme sensitivity to DNA-damaging agents — standard-dose chemotherapy and radiation can cause fatal toxicity if FA is undiagnosed. Not the same as Fanconi syndrome (a renal tubular disorder).

Background

• Autosomal recessive (most common) or X-linked recessive genetic disorder affecting DNA interstrand crosslink (ICL) repair
• Mutations in at least 22 FA genes (FANCA most common, ~65% of cases)
• Prevalence approximately 1:350,000 births; carrier frequency ~1:300 in European/US populations
• Higher carrier frequency in Ashkenazi Jewish, Afrikaner, and Spanish Romani populations
• Median age of diagnosis: 6-8 years; ~25% of patients have NO congenital anomalies and may not be diagnosed until adulthood
• 90% develop bone marrow failure by age 40
• Median mortality age ~20 years (improving with modern transplant techniques)
• Leading causes of death: bone marrow failure > malignancy (AML/MDS, head/neck squamous cell carcinoma) > complications of transplant

Clinical features

What the EM physician will see

• FA patients most commonly present to the ED with complications of pancytopenia:

Hemorrhagic emergencies

• Epistaxis (often recurrent and severe)
• Mucocutaneous bleeding, petechiae, purpura, ecchymoses
• GI hemorrhage
• Intracranial hemorrhage (particularly dangerous; high-impact activities should be avoided in thrombocytopenic patients)
• Menorrhagia in adolescent/adult females
• Prolonged bleeding from wounds, dental procedures, or minor trauma

Infectious emergencies

• Febrile neutropenia — the most dangerous acute presentation; treat as per standard febrile neutropenia protocols
• Recurrent bacterial infections (pneumonia, skin infections, sinusitis, UTIs)
• Oral candidiasis, fungal infections (in severe neutropenia)
• Sepsis

Anemia-related symptoms

• Fatigue, weakness, dyspnea on exertion
• Dizziness, syncope, tachycardia
• Pallor
• High-output cardiac failure (rare, with very severe chronic anemia)

Congenital anomalies (present in ~75%)

• Useful for recognizing the undiagnosed FA patient presenting to the ED:
• Skeletal: absent or hypoplastic thumbs, absent/hypoplastic radii (always with thumb abnormalities), short stature, vertebral anomalies
• Skin: café au lait spots (>50%), diffuse hyperpigmentation, hypopigmented patches
• Head: microcephaly (25%)
• Eyes: microphthalmia, strabismus, epicanthal folds
• Ears: hearing loss (usually conductive), low-set or malformed ears
• Renal: structural anomalies (horseshoe kidney, ectopic kidney, absent kidney) — 20%
• Cardiac: congenital heart defects — 5%
• GI: tracheoesophageal fistula, esophageal/duodenal atresia, imperforate anus
• Genitourinary: cryptorchidism, hypospadias, micropenis (males); structural uterine/vaginal anomalies (females)
• VACTERL-H phenotype (vertebral, anal, cardiac, tracheoesophageal, renal, limb + hydrocephalus) found in ~12%
• 25% of FA patients have NO physical anomalies — suspect FA in any young patient with unexplained pancytopenia

Malignancy

• AML/MDS: ~30% lifetime risk; may be the initial presentation of previously undiagnosed FA
• Head and neck squamous cell carcinoma: greatly increased risk, particularly after stem cell transplant and in patients with graft-versus-host disease
• Gynecologic malignancy: vulvar and cervical SCC
• Liver tumors: hepatocellular carcinoma, hepatic adenomas (particularly in patients treated with androgens)
• Critical EM pitfall: if an FA patient presents with leukemia or a solid tumor and is given standard-dose chemotherapy or radiation, extreme and potentially fatal myelosuppression will result due to impaired DNA repair

Differential diagnosis

Other inherited bone marrow failure syndromes

• Dyskeratosis congenita
• Diamond-Blackfan anemia
• Shwachman-Diamond syndrome
• Thrombocytopenia-absent radius (TAR) syndrome

Other causes of pancytopenia

• Aplastic anemia (acquired)
• Myelodysplastic syndrome
• Acute leukemia
• Megaloblastic anemia (B12/folate deficiency)
• HIV
• Drug-induced myelosuppression
• Systemic lupus erythematosus

Evaluation

EM workup (acute presentations)

• CBC with differential and peripheral smear:
  • Macrocytosis (elevated MCV — often the earliest hematologic abnormality; precedes cytopenias)
  • Elevated fetal hemoglobin (HbF)
  • Thrombocytopenia (usually appears first)
  • Leukopenia/neutropenia
  • Anemia (develops later)
  • Smear: macrocytes, occasional target cells; blast cells if AML transformation
• Reticulocyte count: low (hypoproliferative anemia)
• Type and screen — anticipate transfusion needs
• BMP: electrolytes, renal function (structural renal anomalies are common)
• LFTs: hepatic adenomas and iron overload from chronic transfusion
• Coagulation studies: if active bleeding
• Blood cultures (at least 2 sets from separate sites) — before antibiotics if febrile neutropenia
• Urinalysis, chest radiograph — as indicated by clinical presentation
• Lactate, procalcitonin — if sepsis suspected
• ECG — if congenital heart disease or cardiomyopathy suspected

When to suspect undiagnosed FA in the ED

• Young patient with unexplained pancytopenia + macrocytosis ± congenital anomalies
• Patient with unexpected severe toxicity from standard-dose chemotherapy or radiation
• Early-onset malignancy (AML in a child/young adult; head/neck SCC in a young non-smoker)
• Diagnosis is confirmed by chromosomal breakage (fragility) test using diepoxybutane (DEB) or mitomycin C — this is not an ED test but should be arranged via hematology consultation

Management

Hemorrhagic emergencies

• Platelet transfusion:
  • Use single-donor platelets (reduces alloimmunization risk)
  • Leukodepleted (CMV risk reduction)
  • Irradiated (prevents transfusion-associated graft-versus-host disease)
  • Do NOT use blood products from family members — may sensitize the patient and compromise future stem cell transplantation
  • Transfuse for active bleeding or platelets <10,000/μL (or <50,000/μL if surgery/invasive procedure planned)
• Avoid:
  • NSAIDs and aspirin (impair platelet function)
  • IM injections (hematoma risk)
  • Rectal thermometers, suppositories, enemas (mucosal trauma)
• Epistaxis: topical hemostatic agents, anterior packing; avoid posterior packing if possible due to mucosal fragility
• Aminocaproic acid (Amicar) or tranexamic acid: may be used as adjunctive antifibrinolytic therapy for mucosal bleeding

Febrile neutropenia

• Manage per standard Febrile neutropenia protocols — this is a medical emergency
• Fever (≥38.3°C single or ≥38.0°C sustained) + ANC <500/μL (or expected to fall below 500/μL)
• Empiric broad-spectrum antibiotics within 1 hour of presentation (e.g., cefepime, piperacillin-tazobactam, or meropenem per institutional protocol)
• Blood cultures before antibiotics (do not delay antibiotics for cultures if not immediately obtainable)
• Low threshold for antifungal coverage if not responding to antibiotics within 48-72 hours
• G-CSF (filgrastim) may be used for neutropenia-related infectious complications with ANC <500/μL

Anemia

• Packed RBC transfusion:
  • Leukodepleted, irradiated (same principles as platelets)
  • Do NOT use family member donors
  • Transfusion threshold depends on clinical context; generally for hemoglobin <7 g/dL or symptomatic anemia
• Monitor for transfusional iron overload in chronically transfused patients — serum ferritin, cardiac and hepatic MRI T2*

Airway considerations

• Skeletal anomalies (vertebral, mandibular) may make intubation difficult
• Short stature may require smaller-than-expected equipment
• Avoid nasal intubation if thrombocytopenic (nasal bleeding risk)
• Avoid nitrous oxide (suppresses bone marrow via impaired methionine synthetase)

Medication safety

• Avoid NSAIDs and aspirin
• Avoid IM injections
• FA patients receiving androgens (oxymetholone, danazol) for bone marrow stimulation may have: hepatic dysfunction (peliosis hepatis, adenomas), virilization, lipid abnormalities — consider when interpreting labs
• If cancer is diagnosed or suspected, do NOT initiate standard-dose chemotherapy or radiation in the ED — consult hematology/oncology experienced in FA management; profoundly reduced doses are required

Disposition

• Febrile neutropenia: admit; ICU if hemodynamically unstable or severely septic
• Active hemorrhage with severe thrombocytopenia: admit to monitored setting; hematology consultation
• Severe anemia (Hb <7 g/dL) or symptomatic: admit for transfusion and evaluation
• New pancytopenia of unknown cause: admit or arrange urgent hematology follow-up; do not discharge without a plan for workup
• Stable known FA patient with mild cytopenias: may discharge with close hematology follow-up and clear return precautions for fever, bleeding, syncope, or worsening weakness
• All FA patients: ensure hematology is involved in care and aware of the ED visit
• Educate patients/families:
  • Return immediately for any fever (even low-grade if neutropenic)
  • Avoid contact sports and high-impact activities (head trauma risk with thrombocytopenia)
  • Avoid NSAIDs
  • Wear medical identification

See Also

• Fanconi syndrome (a completely different condition — renal tubular disorder)
• Pancytopenia
• Febrile neutropenia
• Aplastic anemia
• Thrombocytopenia
• Acute myeloid leukemia

External Links

• StatPearls — Fanconi Anemia
• GeneReviews — Fanconi Anemia
• Fanconi Anemia Research Fund — Clinical Care Guidelines
• Medscape — Fanconi Anemia
• NORD — Fanconi Anemia