A 68-year-old man has had low back pain over the past 2 months. Laboratory studies show a normochromic, normocytic anemia and azotemia. Serum and urine calcium concentrations are abnormally increased, and urinalysis shows excessive protein (4+) and proteinaceous casts. Bone marrow examination is most likely to show uncontrolled proliferation of which of the following cells?
Basophils
Lymphocytes
Macrophages
Plasma cells
Reticulocytes
Correct answer
Plasma cells
Feedback
correct answer: D
The patient described has multiple myeloma, which is characterized by proliferation of plasma cells and hyperproduction of monoclonal light chains (Bence-Jones proteins). Accumulation at the renal tubules causes renal insufficiency. MM also causes bone destruction, both from marrow expansion and stimulation of osteoclasts. This causes hypercalcemia, which also contributes to renal dysfunction. As with any leukemia, other cell lines are suppressed, causing anemia and thrombocytopenia.