Plasma Cell Tumors

Plasma cell tumors represent a spectrum of diseases characterized by clonal proliferation of homogeneous immunoglobulin-producing plasma cells or B cells. They encompass clinically indolent conditions such as monoclonal gammopathy of unknown significance and Waldenström's macroglobulinemia, as well as malignant processes including multiple myeloma (MM) and solitary plasmacytoma (solitary osseous plasmacytoma and extramedullary plasmacytoma (EMP)). In dogs with MM, the short-term prognosis is good in respect to initial tumor control and improvement of quality of life. EMP is a neoplastic plasma cell tumor originating from soft tissues in the absence of primary bone marrow disease and both cutaneous and noncutaneous forms have been described. Cutaneous plasmacytosis is generally considered a benign process with indolent behavior; therefore, therapy is usually reserved for patients with clinical signs or compromised quality of life. Waldenström's macroglobulinemia differs from MM in that bone lysis is generally absent and hepatosplenomegaly, lymphadenopathy, or both are frequently encountered clinical findings.