Intracytoplasmic lumina and mucinous inclusions in ovarian carcinomas

Intracytoplasmic mucinous inclusions and lumina have been previously described in non-glandular neoplasms such as urothelial carcinoma. We describe their presence in 93% of non-mucinous ovarian carcinomas. They were found in abundance in all 25 cases (100%) of clear cell carcinoma, in 48 of 50 cases (96%) of serous carcinoma and 20 of 25 cases (80%) of endometrioid carcinoma. The degree of the differentiation of the tumour did not influence the number of inclusions or lumina observed. These results suggest that the presence of intracytoplasmic lumina and mucinous inclusions is more widespread than hitherto appreciated. Their presence in an otherwise poorly differentiated metastatic carcinoma might, at the very last, prompt one to consider the ovary as a possible primary site. In addition, an abundance of intracytoplasmic mucinous inclusion and lumina with microcyst formation, in an otherwise poorly differentiated malignant primary ovarian epithelial tumour, might suggest the possibility of a clear cell carcinoma.