Primary low-grade B-cell lymphoma of mucosa-associated lymphoid tissue type arising in the urinary bladder - Report of 4 cases with molecular geneticanalysis

Context.-Primary lymphoma of the urinary bladder is rare. Only 84 cases hav e been reported in the English literature to date, and none of these cases has had molecular confirmation of clonal immunoglobulin gene rearrangement. Objectives.-To review all cases with primary urinary bladder lymphoma in ou r records, to classify them using the REAL classification, to confirm their immunophenotype and genotype, and to determine their outcome. Design.-We identified 4 cases of primary urinary bladder lymphoma in our me dical records from a 30-year period. Immunohistochemical detection of immun oglobulin light chains and molecular analysis of immunoglobulin heavy-chain genes using the polymerase chain reaction were performed on paraffin-embed ded material. Results.-All patients were older than 60 years. The male-female ratio was 1 :3. All patients had a history of chronic cystitis. Histologic features of mucosa-associated lymphoid tissue lymphoma with centrocyte-like cells, plas macytoid B cells, or both were observed in all cases. Monoclonality of B ce lls was demonstrated by immunohistochemistry, polymerase chain reaction, or both methods in every case. All patients presented with stage IAE disease, were treated with radiotherapy alone, and have been in continuous complete remission for 2 to 13 years. Conclusions.-Primary bladder lymphomas are usually of low-grade mucosa-asso ciated lymphoid tissue type. They are more common in females and are associ ated with a history of chronic cystitis. Lymphoepithelial lesions are seen only in association with areas of cystitis glandularis. B-cell clonality is readily demonstrable by immunohistochemistry and/or polymerase chain react ion analysis. Local radiotherapy appears to confer long-term control.