Abstract

To date, mucoid cytoplasmic inclusions in urothelial carcinomas have rarely been noted. However, we were impressed by the fact that these corpuscles are readily detectable in numerous urothelial neoplasms. Therefore, a histologic analysis of 100 cases of urothelial carcinomas was performed. Overall, 37 cases revealed periodic acid-Schiff-positive cytoplasmic inclusions. These were observed in 14% of grade 1, 49% of grade 2, and 63% of grade 3 carcinomas. The inclusions were histochemically, immunohistochemically, and ultrastructurally identified as cytoplasmic deposits of mucoid materials. Two types of deposits, condensed and noncondensed, could be distinguished. The demonstration of mucoid deposits in otherwise poorly differentiated metastatic carcinomas may be of some differential diagnostic importance insofar as urothelial carcinoma has to be considered as the possible primary tumor.