Aplastic Anaemia Overview Quiz

Guidelines for Adult Aplastic Anemia

• This guideline provides healthcare professionals with clear guidance on managing adult patients with aplastic anemia (AA).
• Key recommendations cover definition, severity, and presentation of AA.

Background

• AA is defined as pancytopenia with a hypocellular bone marrow, lacking abnormal infiltrates or fibrosis.
• It's a rare, heterogeneous disorder, peaking in the age ranges of 10-25 and over 60.
• To diagnose AA, at least two of the following must be present:
  • Hemoglobin concentration below 100 g/L
  • Platelet count less than 50 x 10⁹/L
  • Neutrophil count below 1.5 x 10⁹/L
• Reticulocyte count is helpful in evaluating the severity of AA.

Clinical Assessment

• AA patients often present with symptoms of anemia and thrombocytopenia.
• Serious infections are less common early on.
• Hepatosplenomegaly or lymphadenopathy are usually absent, except during infection.
• A prior history of jaundice may suggest post-hepatic AA.
• A thorough drug, occupational exposure, and family history are essential.

Additional Information

• Most cases of AA are idiopathic, necessitating a drug history investigation.
• Any suspected causative drug should be discontinued and reported to the MHRA using the Yellow Card Scheme.
• Expert advice is recommended for uncertain diagnoses, or in cases involving bone marrow failure syndromes.
• Severity must be assessed using Comitta criteria.

Comitta Criteria

• Severe AA (SAA): Marrow cellularity of less than 25% (or 25%-50% with less than 30% residual hematopoietic cells), and at least two of the following:
  • Neutrophil count less than 0.5 x 10⁹/L
  • Platelets below 20 x 10⁹/L
  • Reticulocyte count below 60 x 10⁹/L (measured by an automated count).
• Very severe AA (VSAA): Same as SAA, but with neutrophils less than 0.2 x 10⁹/L.
• Non-severe AA (NSAA): Does not meet the criteria for SAA or VSAA.

Investigations

• Initial investigations aim to rule out other causes of pancytopenia and hypocellular bone marrow (BM).
• Important investigations include screening for inherited bone marrow failure syndromes.
• Examinations for underlying causes, cytogenetic abnormalities, and paroxysmal nocturnal hemoglobinuria (PNH) clones are essential.

1-Full Blood Count

• Pancytopenia: Hemoglobin, neutrophils, and platelets are commonly depressed.
• Isolated Cytopenia: Particularly thrombocytopenia, can occur in the initial stages.
• Preserved Lymphocytes: Usually present in normal amounts.
• Monocytopenia: May indicate further investigation for hairy cell leukemia or inherited bone marrow failure.

2- Reticulocyte Count

• Automated counts can overestimate reticulocytes, so Comitta's criteria are crucial.
• Reticulocyte counts should be below 60 x 10⁹/L (using automated methods).

3- Blood Film Examination

• Macrocytosis and anisopoikilocytosis: Often observed.
• Toxic Granulation: Neutrophils may show toxic granulation.
• Platelet Size: Primarily small platelets are often observed.
• Abnormal Cells: Dysplastic neutrophils, unusual platelets, blasts, or other abnormal cells should be excluded.

4- Haemoglobin F Percentage

• HbF measurements are taken pre-transfusion.
• Constitutional syndromes often show elevated HbF.

5- Peripheral Blood Chromosomal Breakage Analysis (DEB Test)

• Used to investigate possible Fanconi anemia in patients younger than 50.
• Additional screenings are for older patients when Fanconi anemia is suspected.

6- Flow Cytometry for GPI-Anchored Proteins

• Detects PNH clones using fluorescent aerolysin (FLAER).
• Necessary steps include correcting any documented vitamin B12 or folate deficiencies before confirming a diagnosis of AA.

7- Vitamin and Folate Levels

• Corrected vitamin B12 or folate deficiencies should be documented before reaching a final AA diagnosis.
• Bone marrow aplasia from vitamin deficiencies is rare.

8- Liver Function Tests

• Necessary to identify any antecedent or ongoing hepatitis.

9- Viral Studies (Hepatitis, EBV, CMV, HIV, Parvovirus)

• AA due to hepatitis is rare, often occurring 2–3 months after an acute hepatitis episode.
• It's more common in young men.
• In post-hepatitis AA, serology is often negative for known hepatitis viruses; CMV assessment is recommended if HSCT is being considered.
• HIV commonly causes isolated cytopenias but is a very rare cause of AA in general.
• Parvovirus B19 is usually associated with pure red aplasia, but rarely with AA.

10- Anti-nuclear Antibody (ANA)/Double-stranded DNA (dsDNA)

• Pancytopenia can present in systemic lupus erythematosus (SLE) with autoimmune features or myelofibrosis.
• Hypocellular bone marrow is also possible in SLE, although less common.

11- Chest X-ray and Other Radiology

• Helpful for excluding infection and comparing to subsequent films.
• Used to evaluate for bone marrow failure syndrome (IBMFS) if needed.
• High-resolution CT chest scan can identify lung fibrosis if needed.

12- Abdominal Ultrasound and Echocardiogram

• Enlarged spleen and/or lymph nodes suggest a possible (neoplastic) hematological problem.
• Abnormal or displaced kidneys may indicate Fanconi anemia, especially in younger patients.

13- Genetic Testing (PB&BM)

• Next-generation sequencing (NGS) panel of genes can be used to detect or monitor myeloid neoplasms and detect clonal evolution.
• Somatic gene mutations are present in 20–30% of cases, particularly as the disease progresses.
• These tests are used to distinguish AA from hypocellular MDS.

14- Telomere Length

• Peripheral blood leucocytes are used for screening telomere gene mutations, especially in chronic dyskeratosis congenita
• Less specific when used in adult-onset AA with TERT/TERC mutations. Telomeres may also be reduced in acquired cases with reduced stem cell reserve.

Bone Marrow Aspirate & Biopsy

• An adequate bone marrow aspirate and trephine biopsy (>1.5 cm) is essential for diagnosis.
• Investigations must exclude other causes of pancytopenia with hypocellular marrow.
• AA must be differentiated from hypo-plastic MDS by histologic/cytogenetic analysis.

Bone Marrow Findings

• Difficulty obtaining fragments may indicate marrow fibrosis or infiltration.
• AA BM fragments show hypocellularity, prominent fat spaces, and residual hematopoietic cells.
• Erythropoiesis is reduced or absent, often with dyserythropoiesis.
• Megakaryocytes and granulocytes are noticeably reduced (or absent).
• Mast cells may be seen in normal quantities.
• Increased macrophages with background eosinophilia can (potentially) indicate interstitial oedema.

Cytogenetic and Karyotyping

• Traditional karyotyping may be unsuccessful in very hypocellular samples.
• FISH analysis for chromosomes 5, 7, 8, and 13 should be performed in these cases.
• Abnormalities like del(13q) or trisomy 8 can occur in AA, whereas others can be transient
• In children, monosomy 7 can suggest MDS, but it's also possible in adults with AA.
• A new abnormal cytogenetic finding indicates clonal evolution.
• Other methods like SNP analysis and whole genome scanning might be used to find chromosomal defects.

Bone Marrow Biopsy (Further Details)

• Good quality, at least 2 cm, trephine biopsies are essential to assess overall cellularity and morphology of residual hematopoietic cells.
• Tangential biopsies should be avoided, as subcortical marrow is typically hypocellular.
• In most cases, hypocellularity is observed throughout. but patchy hypocellular and residual cellular areas might present.
• Average cellularity should be below 30% after excluding lymphocytes and plasma cells.
• Focal hyperplasia (increased production) of erythroid or granulocytic cells at similar stages of maturation might appear.
• Small lymphoid aggregates can, but only occasionally, be present in cases of associated systemic autoimmune diseases, like rheumatoid arthritis. Increased reticulin staining, abnormal megakaryocytes or blasts are NOT typical of AA. Their presence implies h-MDS or leukaemic transformation.

Other Causes of Pancytopenia and Hypocellular Bone Marrow

• PNH (paroxysmal nocturnal hemoglobinuria) is a possible association.
• Further tests for peripheral blood immunophenotyping for GPI-linked molecules in red and white cells may be necessary.
• Small accumulations of immature granulocytes might occur during AA regeneration.
• Dyserythropoiesis and other atypical features are common in cases and do not distinguish it from MDS

Hodgkin/Non-Hodgkin Lymphoma

• Similar cases with pancytopenia and a patchy hypocellular BM may occur with lymphoid infiltration, which may easily be missed.
• Care should be taken to examine the specimen for foci of lymphoma cells or fibrosis.
• Immunophenotyping and gene rearrangement studies exclude lymphoma diagnoses.
• Additional features, such as splenomegaly, lessen the probability of AA.

Infection (e.g., ITP, GATA2 deficiency, MonoMac)

• AA can present with isolated thrombocytopenia. In some cases, pancytopenia might occur later.
• Patients may be misdiagnosed initially as having ITP.
• Cases with absent or reduced megakaryocytes in hypoplastic marrow are highly suspicious, less common)

Recommendations for PNH and AA.

• All AA patients should be screened with flow cytometry to detect GPI-anchored protein deficiencies (CD14, CD16, CD24, FLAER).
• CD55 and CD59 testing is also required, for red cells.
• Initial tests should be performed at diagnosis following a 6 month interval followed by annual tests for PNH unless signs develop.
• Frequency can potentially be reduced if the proportion of PNH cells remains stable.
• Small PNH clones may occur in 50% of patients without noticeable haemolysis.
• Refer new PNH patients to the National PNH service for further monitoring and anti-complement therapy if needed.

Recommendations for Hypocellular Myelodysplastic Syndrome (MDS)

• Most cases of MDS have normocellular or hypercellular bone marrow, but a 10–20% have hypocellularity, recognized as a separate code and subtype.
• Hypocellular MDS share clinical characteristics with aplastic anemia such as macrocytosis and various degrees of dyserythropoiesis.

Quantitative CD34 Enumeration

• A method of discriminating between AA and h-MDS
• High-risk mutations like RUNX1 and abnormalities on chromosome 7 may indicate a risk in progressing to MDS.

Somatic Mutations and the Clinical Implications

• Somatic mutations at diagnosis or during treatment are not uncommon in AA.
• The presence of such mutations shouldn't be interpreted as a definitive indication of MDS transformation.

Treatment Options Recommendations

• The choice of treatment for severe/very severe AA depends on patient age (<40, >40, >60), and availability of HLA-compatible donors.
• First-line treatment for patients under 40 with AA involves HLA-identical sibling transplant if available. If not, alternative treatments include chemotherapy and immunosuppressives.
• For patients over 40, ATG combined with ciclosporin, potentially with eltrombopag, is a common first-line treatment.
• If this doesn't work, matched unrelated allografts are alternatives. Other immune-suppressive alternatives also exist.

AA in the Elderly

• Treatment is more complex as comorbidities and treatment toxicity influence quality of life and needs to be considered.
• Hypocellular MDS, which is quite common in older age patients with AA cases, must be considered.
• Careful consideration of patient fitness for ATG is paramount.

Management of Pregnancy (AA)

• Ob/gyn and hematology consultation is necessary during pregnancy to identify potential relapse and plan treatment options.
• Mild anemia and thrombocytopenia in pregnancy needs to be carefully evaluated, and underlying causes (such as iron/vitamin deficiency) need to be excluded.
• Cytopenias with 14% transfusion dependence happen as a result of during pregnancy in 1/3 of patients.

Haemopoietic Stem Cell Transplantation (HSCT)

• HLA-typing is a diagnostic step to identify compatible donors.
• HLA-matched sibling donors are favored in younger patients.
• For individuals over 40 who are not suitable/available, unrelated donor HSCT is an option
• Detailed pre-transplant work up, including assessing comorbidities, selecting the correct conditioning regimen, and donor selection is essential

Pretreatment Work-up

• Confirming the diagnosis and, if applicable, evaluating clonal evolution.
• Assessment of patient comorbidities.
• Selection of a suitable donor, conditioning regimen, and stem cell source/dose.

Inherited AA Recommendations

• Chromosomal breakage analysis can test for Fanconi Anemia following diepoxybutane (DEB) exposure.
• Assessment should include family history, abdominal scans, echocardiograms, high-resolution chest CT, and pulmonary function tests and investigations to evaluate extra-haematopoietic abnormalities.
• PNH clones in all cell lineages help exclude inherited AA.

Genetic Testing

• Testing identifies constitutional disorders in affected individuals and allows surveillance.
• This testing can reveal associated abnormalities, assess the risks of close relatives, and provide prenatal diagnosis.
• Variants of unknown significance need further investigation, probably combined with family studies.

Management- Supportive Care

• Restrictive red blood cell thresholds (70-80 g/L Hb) are recommended with higher values (80 g/L) for patients with cardiovascular issues
• Rh and Kell blood type matching
• Managing complications for iron overload (alloimmunization and iron overload)

Management- Platelet Transfusions

• Avoid platelet transfusions for asymptomatic patients with chronic thrombocytopenia, unless they have stable disease and currently receiving active treatment.
• Maintain platelet counts above 10 x 10⁹/L in stable patients and 20 x 10⁹/L during ATG therapy, and importantly during sepsis
• HLA allo-immunization causes increased post-HSCT graft rejection.

Management- Iron Chelation Therapy

• Patients undergoing needed regular blood transfusions will gradually develop iron overload.
• Deferasirox needs to be used with caution in AA, particularly in combination with ciclosporin.
• Deferiprone is efficacious but should not be used in neutropenic patients.

Management- Infections

• Severely neutropenic hospitalized AA patients should be isolated.
• Prophylactic antibiotics (eg., quinolones) and empirical antifungal therapy are essential.

Other Treatments of AA

• Erythropoietin and granulocyte colony- stimulating factor (G-CSF) are often ineffective for AA.
• Vaccinations and psychological support should be considered.

Test your knowledge on aplastic anaemia through this quiz. It covers its primary characteristics, age distribution, diagnostic criteria, and guidelines from the British Society for Haematology. Perfect for students and professionals in the medical field.