Solitary extramedullary plasmacytoma of the bladder: a case report and literature.

Plasmacytoma is a rare B-lymphocyte neoplastic disorder that usually presents as the generalized disease multiple myeloma. Less than 5% of the cases present as a solitary mass of monoclonal plasma cells in the bone or soft tissue. Although solitary extramedullary plasmacytoma (SEP) may arise in any organ, it rarely involves the urinary bladder. A 67-year-old male without a history of multiple myeloma presented with urinary frequency and nocturia; he was later diagnosed with SEP of the bladder. The patient was initially treated with a course of radiation therapy without symptomatic improvement; therefore a chemotherapy regimen consisting of lenalidomide and dexamethasone was subsequently given for six cycles. SEP usually carries a better prognosis and higher cure rate than solitary plasmacytoma of bone, as SEP is radiation sensitive. The role of adjuvant chemotherapy in the treatment of SEP that is resistant to radiation therapy is not clear, since most of the recommendations have been derived from the experience of head and neck SEP. The literature also lacks recommendations for choice of a chemotherapy regimen and surveillance of isolated bladder plasmacytoma. Here we present the first case of a radiation-resistant solitary plasmacytoma of the bladder that was successfully treated with lenalidomide and dexamethasone with successful clinical remission.