A 62-year-old man has had back pain for 4 months. No abnormal findings are noted on physical examination. A CBC shows a WBC count of 3700/microliter, hemoglobin 10.3 g/dL, hematocrit 31.1%, MCV 85 fL, and platelet count 110,000/microliter. His total serum protein is 8.5 gm/dl with an albumin of 4.1 gm/dl. A chest radiograph shows no abnormalities of heart or lung fields, but there are several lucencies noted in the vertebral bodies. A sternal bone marrow aspirate is performed and yields a dark red jelly-like material in the syringe. Which of the following cell types is most likely to be numerous on microscopic examination of this aspirate?
The patient has multiple myeloma. The bone marrow needle was in a lytic lesion filled with plasma cells. His serum globulin is high as a result of his monoclonal gammopathy.
Incorrect 1. Giant cells may be seen in a variety of benign and malignant lesions of bone, but this does not explain the hypergammaglobulinemia.
Incorrect 2. Fibroblasts produce collagen and are more numerous with the gross appearance of firm, white scar tissue.
Incorrect 3. Osteoblasts are most numerous in repair of bone, and callus is very firm.
Giant cells
Fibroblasts
Osteoblasts
Plasma cells