LYMPHOMAS OF MUCOSA-ASSOCIATED LYMPHOID-TISSUE ARISING IN THE URINARY-BLADDER

The clinical, histological and immunohistochemical findings in five pr imary lymphomas of the urinary bladder are reported. One patient had b oth lymphoma and transitional cell carcinoma of the bladder. All of th e lymphomas showed histological features of mucosa-associated lymphoid tissue (MALT) lymphomas with centrocyte-like cells in all cases. One patient with pre-existing cystitis glandularis showed lymphoepithelial lesions. Biopsies from four patients contained reactive germinal cent res and, in two of these, there was follicular colonization by tumour cells. In three patients, repeat biopsies, over several years, showing the changes of MALT lymphoma, were diagnosed as cystitis. We suggest that a large proportion of primary lymphomas of the bladder are lympho mas of MALT and that the characteristic morphological and immunohistoc hemical features of these tumours should be sought in biopsies contain ing large numbers of lymphoid cells.