Solitary Plasmacytoma : Bone
Definition: Solitary plasmacytoma of bone is a localized clonal proliferation of immunoglobulin producing plasma cells. By definition, there is no bone marrow involvement at other sites. The clinical features of multiple myeloma are absent. There is no evidence of widespread bone lesions by skeletal survey. Renal failure, anemia and hypercalcemia are not present. There may be low levels of serum/urine M component in about 50% of cases. The levels of polyclonal immunoglobulins in serum are normal. Locations: The most commonly involved location is thoracic spine (40% to 50% cases), followed by lumbar/cervical spine, skull, ribs, pelvis, clavicle, scapula, and femur. About 5% of patients with "solitary" plasmacytoma of bone have multiple lesions but still lack clinical features of multiple myeloma. This image shows solitary plasmacytoma involving a rib. The tumor has solid, fleshy, yellow-tan areas as well as soft, red gelatinous foci. Image courtesy of: Pedro Aleixo, MD, PhD; used with permission.