A 19-year-old university student presents to the Emergency Department for assessment of outpatient laboratory abnormalities. Over the last 2 weeks he has felt significant fatigue and shortness of breath on exertion. He is otherwise healthy with no past medical history or medication use.
- What other investigations would you order?
- What are common medications associated with neutropenia?
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Diagnosis: B-cell acute lymphoblastic leukemia
(B-ALL)
CBC Clues:
(1) Lymphocytosis (note: analyzer error)
(2) Abnormal lymphocyte cells
(3) Anemia, thrombocytopenia, neutropenia
CBC Pearls
A peripheral blood smear review is essential to confirm most abnormal CBC findings
Q1: What other investigations would you order?
Peripheral blood smear, flow cytometry, bone marrow biopsy
Q2: What are common medications associated with neutropenia?
Anti-thyroid, antibiotics, antivirals, antipsychotics
Acute lymphoblastic leukemia (ALL) is a hematologic malignancy that arises from a B- or T-lymphocyte precursor. Proliferation of these malignant cells in the bone marrow results in cytopenias, as seen here. ALL can also accumulate in extramedullary sites, including meninges, gonads, thymus, spleen, and lymph nodes.
This patient’s high lymphocyte count may initially seem like a chronic, mature process (e.g. CLL). However, automated CBC analyzers cannot always differentiate normal from abnormal cells. Therefore, a peripheral blood smear review is essential to confirm the CBC findings. In this case, the mature lymphocytes were more in keeping with lymphoblasts on smear review. Additional diagnostics should include flow cytometry and bone marrow biopsy. The differential diagnosis includes viral infection (e.g. EBV), aplastic anemia, and APML.
Definitive ALL management varies based on cell genetic and immunologic characteristics. Initial treatment involves supportive care, including blood products. Neutropenic patients should be monitored for febrile neutropenia. Finally, cytoreductive therapy (e.g. hydroxyurea) can be considered while diagnostics are pending.