Case History:
A 64 year old female admitted after routine primary care visit revealed leukocytosis (94 x 10^3/cm).
Flow cytometry on peripheral blood: CD45-negative tumor population that was negative for all lineage defining antigens.
Bone marrow biopsy: Hypercellular (>90% cellularity) with sheets of tumor cells that are CD138 positive.
Diagnosis: Plasma cell leukemia
What is the percentage of circulating plasma cells required for this diagnosis?
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>5%
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>10%
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>15%
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>20%
Answer: >5% (WHO 5th edition)
Case contributed by: Michael Robinson, D.O., Hematopathology Fellow