Plasma cell neoplasms. Review of disease progression and report of a new variant.

Plasma cell neoplasms are generally categorized into four groups; multiple myeloma (MM), solitary plasmacytoma of the bone (SPB), plasma cell leukemias, and extramedullary plasmacytomas (EMP). A plasmacytoma is defined as any discrete, usually solitary mass of neoplastic plasma cells, either in the bone marrow or in various soft tissue sites. Each manifestation of a plasma cell neoplasm differs in terms of tumor recurrence and progression to MM. A gastric plasmacytoma (GP) is a rare presentation of extramedullary plasmacytoma and has not been previously reported as a site of recurrence for a SPB. This pattern of tumor recurrence is unique and the management of gastric plasmacytoma as part of this complex disease is discussed. The continuum of progression between various sites and manifestations of plasma cell manifestations is reviewed including a previously undiscovered sequence of bone disease, gastric disease, and finally multiple myeloma.