What investigations should be sent after taking a bone marrow biopsy in a patient with severe pancytopenia?

Investigations to Send After Bone Marrow Biopsy in Severe Pancytopenia

For a patient with severe pancytopenia, a comprehensive panel of investigations should be sent along with the bone marrow biopsy, including cytogenetics, flow cytometry, and specialized stains to determine the underlying etiology. 1

Core Investigations

Morphological Assessment

• Bone marrow aspirate and trephine biopsy should be evaluated together, with the highest percentage of abnormal cells from either procedure being recorded for diagnostic purposes 1
• CD138 stains should be used when plasma cell disorders are suspected to accurately determine plasma cell percentage in bone marrow biopsies 1
• Special stains including Prussian blue for iron stores and reticulin for fibrosis should be performed routinely 1

Cytogenetic Studies

• Standard metaphase cytogenetics (karyotyping) should be performed on all bone marrow samples despite its lower yield (approximately 20%), as it provides important prognostic information 1
• Fluorescent in situ hybridization (FISH) should be performed, preferably on purified marrow tumor cells, with probes that include:
  • For suspected myeloma: chromosome 17p13, t(4;14), t(14;16) 1
  • For suspected MDS: del(5q), del(20q), +8, or −7/del(7q) 1

Flow Cytometry

• Immunophenotyping by flow cytometry should be performed to:
  • Establish clonality of plasma cells in suspected myeloma 1
  • Detect abnormal CD34+ expression in suspected MDS 1
  • Screen for paroxysmal nocturnal hemoglobinuria (PNH) clone, particularly in young patients with hypoplastic marrow 1
  • Assess for lymphoid neoplasms 2, 3

Disease-Specific Investigations

For Suspected Myeloma

• Serum protein electrophoresis and immunofixation 1
• Nephelometric quantification of serum immunoglobulins 1
• 24-hour urine collection for electrophoresis and immunofixation 1
• Serum free light chain assay 1
• Serum β2-microglobulin and lactate dehydrogenase for prognostic assessment 1

For Suspected Myelodysplastic Syndrome

• Complete blood count with reticulocyte count 1
• Serum erythropoietin level 1
• Vitamin B12 and RBC folate levels 1
• Iron studies (serum iron, total iron binding capacity, ferritin) 1
• HLA-DR15 typing (to predict response to immunosuppressive therapy) 1

For Suspected Infectious Causes

• Viral studies including HIV, parvovirus B19 (especially in hypoplastic marrow), CMV, and hepatitis B and C 1
• Blood cultures if febrile 1

Additional Specialized Testing

• Molecular testing for somatic mutations should be considered when available, particularly for suspected myeloid neoplasms 1
• PCR testing for specific pathogens when infection is suspected 1
• Genetic screening for inherited bone marrow failure syndromes in younger patients or those with family history of cytopenias 1

Common Pitfalls to Avoid

• Relying solely on bone marrow aspirate without biopsy can lead to inadequate assessment, especially in fibrotic marrow 2, 4
• Failure to perform cytogenetics and FISH can miss important prognostic markers 1
• Overlooking non-neoplastic causes of pancytopenia such as megaloblastic anemia, which is a common reversible cause 2, 4, 5
• Not sending sufficient material for all necessary studies, particularly when the marrow is hypocellular 3

Clinical Considerations

• The etiology of pancytopenia varies by age group - in children, B-lymphoblastic leukemia is most common, while in adults, myeloid neoplasms (AML and MDS) predominate 3
• Approximately 17-33% of pancytopenia cases are due to megaloblastic anemia, which is treatable and reversible 6, 4, 5
• In cases with nonspecific findings, a repeat bone marrow examination may be necessary after a period of observation 1

By ensuring these comprehensive investigations are performed on bone marrow samples from patients with severe pancytopenia, clinicians can maximize diagnostic yield and guide appropriate treatment decisions.