LAUSR

From 2009-2017, we identified 9 cases of plasma cell neoplasms on biopsies of the bladder in patients without a history of plasma cell myeloma or transplantation (6 male, 3 female). Four of the nine showed amyloid deposition, of which one additionally revealed a clear cell adenocarcinoma of the bladder. Follow-up was obtained in 7 cases. Of 3 cases (including 2 with amyloid) for which electrophoresis and immunofixation results were obtained, the 2 amyloid cases showed evidence of serum or urine paraproteins: serum IgM kappa in a patient with kappa light chain-restricted plasma cell neoplasm and urine IgA lambda in a patient with lambda light-chain restricted plasma cell neoplasm. By contrast, 1 case with a kappa light-chain restricted plasma cell neoplasm in the absence of amyloid showed no serum monoclonal protein. Bone marrow biopsy results were obtained on the 2 amyloid cases revealing a population of 5 percent or less plasma cells with no assessment of clonality, and thus, were not diagnostic of plasma cell myeloma. In congruence, the 2 amyloid cases also showed no radiologic evidence of systemic plasma cell myeloma. One patient with plasma cell neoplasm only received chemotherapy and radiation without subsequent biopsies; one patient with plasma cell neoplasm, amyloid, and clear cell adenocarcinoma received radiation with an absence of neoplastic disease on subsequent biopsies. Additionally, no evidence of systemic amyloid was found in the cases with bladder amyloidosis. Plasma cell neoplasms of the bladder, with and without amyloid deposition, are rare; this is the first known case series. In 7 cases with follow-up, plasma cell myeloma did not appear to manifest in a 1-127 month follow-up. However, paraproteins were identified on further testing in 2 cases with amyloid. While bladder plasma cell neoplasms with and without amyloid tend to have a favorable prognosis in short-term follow-up, our study supports the need for additional workup for systemic disease, particularly in those with concurrent amyloidosis.