High-Grade Urothelial Carcinoma on Urine Cytology Resembling Umbrella Cells.

Context: High-grade urothelial carcinoma (UC) cells have many appearances on urine cytology, but according to The Paris System, they can be easily distinguished from umbrella cells.

Objective: We aimed to define the incidence and appearance of high-grade UC cells that resemble umbrella cells in Cytospin preparations on urine cytology.

Results: Cytospin preparations from 331 cases with biopsy follow-up (230 benign/low-grade and 101 malignant [22 carcinoma in situ, 52 papillary, 19 invasive UC, 8 other] cases) were reviewed. A total of 18 cases with malignant cells resembling umbrella cells were identified (17.8% of the malignant cases) and were the only type of malignant cell in 3% of the cases. Two patterns were identified. Tumor cells were either identifiable by at least 20 abnormal cells which were large, had abundant cytoplasm but an elevated nuclear-to-cytoplasmic ratio, and markedly enlarged, round-to-elongated nucleoli, or else rare cells with abundant cytoplasm but obviously malignant nuclei. Cells without nucleoli or obviously malignant nuclei were not specific.

Conclusions: Malignant cells resembling umbrella cells can be seen in up to 17% of urine cytology specimens.