Plasmacytoma of the Bone

A 55-year-old man complaining of backache had localized tenderness at the paraspinal region over the posterior portion of the right 7th rib. A CT scan of the thorax revealed erosion of this portion of the rib, along with a space-occupying lesion that displaced the adjacent pleura and lung. Needle aspiration and biopsy study of this mass showed it to be a plasmacytoma.

A study of aspirated bone marrow showed no abnormalities, and a complete skeletal survey showed no other bony lesions. Immunoelectrophoresis of serum and urine showed no abnormal proteins, thereby establishing a diagnosis of solitary plasmacytoma of the rib.

Solitary plasmacytomas of the bone are usually located in the spine or the long bones of the extremities. Overt multiple myeloma develops in about 55% of affected patients, usually within 3 to 4 years. Treatment consists of radiation of the involved region. Patients should be checked regularly for subsequent development of multiple myeloma.