A 65-year-old male with fractures and bone pain has bone marrow showing many plasma cells. Which disease should be suspected?

• A. A traumatic bone marrow aspirate collection
• B. Multiple myeloma
• C. Bare lymphocyte syndrome
• D. Hyper-IgM syndrome

Answer: (B)

Plasma cells taking over the bone marrow in an older patient who has bone pain and fractures strongly points to a malignant plasma cell disorder, specifically multiple myeloma. In this disease, a clonal population of plasma cells expands in the marrow and often produces a monoclonal immunoglobulin (the M protein). This abnormal cell growth drives osteoclast activity, leading to lytic bone lesions and fractures, along with symptoms like anemia and possible kidney issues. The finding of many plasma cells in the marrow fits multiple myeloma best for this clinical picture. The other options don’t fit: a traumatic bone marrow aspirate is a sampling issue, and the immunodeficiency conditions listed do not cause clonal plasma cell expansion with destructive bone lesions in an elderly patient.