Which hematologic disorder is cancer of white blood cells?

• A. Lymphoma
• B. Leukemia
• C. Myeloma
• D. Leukopenia

Answer: (B)

Leukemia is cancer of white blood cells. It begins in the bone marrow with malignant white blood cell precursors that proliferate uncontrollably and spill into the bloodstream. These abnormal leukocytes can crowd out normal blood cells, leading to fatigue from anemia, increased infections, and easy bruising or bleeding from a lack of healthy platelets. This distinguishes leukemia from lymphoma, which involves cancerous lymphocytes that commonly form solid tumors in lymph nodes, and from multiple myeloma, which is cancer of plasma cells in the bone marrow affecting antibody production. Leukopenia, by contrast, is simply a low white blood cell count and is not cancer.