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Aplastic anemia

Definition
AA is a rare hematopoietic stem cell disorder that results in pancytopenia and hypocellular bone marrow.
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Pathophysiology
The pathophysiology of AA is largely immune-mediated, with autoreactive lymphocytes mediating the destruction of hematopoietic stem cells. This immune dysregulation leads to bone marrow failure and the cessation of new blood cell production.
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Epidemiology
The incidence of AA is estimated at 0.2-0.3 per 100,000 person-years in Europe.
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Disease course
Clinically, patients may present with symptoms related to anemia, such as fatigue and pallor, bleeding tendencies due to thrombocytopenia, and increased susceptibility to infections due to neutropenia. A significant complication of AA is the risk of progression to myelodysplastic syndromes or acute myeloid leukemia.
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Prognosis and risk of recurrence
The prognosis of AA can vary widely. Some patients may have mild symptoms that require little or no therapy, while others may present with life-threatening pancytopenia.
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Key sources
The following summarized guidelines for the evaluation and management of aplastic anemia are prepared by our editorial team based on guidelines from the British Society for Haematology (BSH 2024; 2018), the North American Pediatric Aplastic Anemia Consortium (NAPAAC 2021), and the Kidney Disease: Improving Global Outcomes Foundation (KDIGO 2012).
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Guidelines

1.Classification and risk stratification

Severity assessment: assess the severity of AA according to the Camitta criteria.
B
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2.Diagnostic investigations

Medication history: elicit a careful medication history and discontinue any putative causative drug, although most cases of AA are idiopathic.
B

More topics in this section

  • Evaluation for inherited AA

  • Screening for paroxysmal nocturnal hemoglobinuria

3.Diagnostic procedures

Bone marrow biopsy
Perform bone marrow aspiration of an adequate sample and trephine biopsy of good length (> 1.5 cm) for the diagnosis of AA and exclusion of other causes of pancytopenia with a hypocellular marrow.
B
Differentiate AA from hypoplastic myelodysplastic syndrome by integrating cytohistological and genetic features.
B

4.Medical management

General principles
Ensure a multidisciplinary team meeting approach to collate relevant results and develop a treatment plan. Consider seeking expert advice on the diagnosis and management where there is uncertainty or when an inherited bone marrow failure syndrome is being considered.
B
Provide psychological support to all patients.
B

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  • Antithymocyte globulin

  • Cyclophosphamide

  • Eltrombopag

  • Iron chelation therapy

  • Antimicrobial prophylaxis

5.Therapeutic procedures

Blood transfusion
Insufficient evidence to recommend RBC transfusion support in patients with AA.
I
Consider using a restrictive transfusion strategy (hemoglobin 70-80 g/L; 80 g/L for patients with CVD) in stable hospitalized patients. Consider adopting individual transfusion plans in outpatients depending on symptoms and comorbidities in line with the limited data in myelodysplastic syndrome.
C

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  • Platelet transfusion

  • Hemopoietic stem cell transplantation

6.Specific circumstances

Pediatric patients, evaluation: obtain the following evaluations in all patients:
Situation
Guidance
Baseline laboratory tests
CBC with differential
Absolute reticulocyte count
Peripheral smear
Serum electrolytes, liver transaminases, total and direct bilirubin
BUN, creatinine
LDH, uric acid
Direct/indirect antiglobulin test (Coombs)
PT, PTT, fibrinogen
Bone marrow aspiration
Morphology
Evaluation for leukemic blasts (flow cytometry unless insufficient cells, with or without appropriate immunostaining)
Iron stain
Cytogenetics
Fluorescent in situ hybridization, including evaluation for 7/del (7q), -5/del (5q), +8, del (20q)
Bone marrow biopsy
Cellularity
Morphology (including immunohistochemical staining for CD34 to evaluate for blasts and CD61 to evaluate for micromegakaryocytes)
Reticulin stain
Infectious diseases
Hepatitis serology (serology for hepatitis A, B, C, and E)
EBV (serology, PCR)
CMV (serology, PCR)
Parvovirus (serology, PCR)
Human herpes virus 6 (PCR)
HIV-1 (antigen/antibody screen)
HSV 1 and 2 (serology)
Varicella (IgG, baseline before treatment)
Immunologic
Immunoglobulins (IgG, IgM, IgA)
Lymphocyte subset immunophenotyping (CD3, CD4, CD8, CD19, CD56)
Rheumatologic
ANA
Complement 3 and 4
Fetal hemoglobin
Hemoglobin F level (hemoglobin electrophoresis or high-performance liquid chromatography)
Paroxysmal nocturnal hemoglobinuria
Paroxysmal nocturnal hemoglobinuria screening panel of RBCs and WBCs (high sensitivity multi-parameter flow cytometry on peripheral blood)
Fanconi anemia
Chromosomal fragility testing (diepoxybutane assay, or mitomycin C as an alternative assay
Dyskeratosis congenita
Telomere evaluation by flow-fluorescent in situ hybridization (6-cell panel, or 2-cell panel if 6-cell panel not readily available)
HLA typing
High-resolution typing in patients, including class I (A, B, C) and class II (DR, DQ, DP)
High-resolution typing on all full siblings (consider obtaining low-resolution typing if high-resolution cannot be obtained or per institutional guidelines)
E

More topics in this section

  • Pediatric patients (management)

  • Elderly patients

  • Pregnant patients

  • Patients with antibody-mediated pure red cell aplasia (evaluation)

  • Patients with antibody-mediated pure red cell aplasia (cessation of ESA therapy)

  • Patients with antibody-mediated pure red cell aplasia (peginesatide)