High-grade urothelial carcinoma in urine cytology: different spaces - different faces, highlighting morphologic variance.

INTRODUCTION: The Paris System for Reporting Urinary Cytology (TPS) was first published in 2016 to standardize reporting and placed a specific emphasis on high-grade urothelial carcinoma (HGUC). The urinary tract is anatomically divided into the upper tract (UT) and the lower tract (LT). A major morphologic criterion in TPS for HGUC defines the nuclear-to-cytoplasmic (N/C) ratio as ≥ 0.7. In this study, we evaluated N/C ratios of HGUC arising from UT and LT urine specimens, to ascertain differences due to location.

MATERIALS AND METHODS: Digital annotations of whole slide scanned images were performed and enumerated.

RESULTS: The cohort consisted of 59 ThinPrep specimens from 52 patients. The majority of the tumors were located in LT (39 of 59, 66.1%). A total of 590 cells were analyzed (10 cells per case). In UT, the average N/C was 0.58 and LT the average was 0.54 (P < 0.001). The average nuclear area for UT was 126.3 and for LT was 158.2 μm (P = 0.01). The average cytoplasmic area for UT was 219.1 μm and for LT was 296.2 μm (P < 0.001). The average cellular circumference for UT was 59.4 μm and for LT was 66.1 μm (P < 0.001).

CONCLUSIONS: We found that UT HGUCs have higher N/C ratios, smaller cell circumference, smaller nuclei, and less cytoplasm compared with LT. When UT was divided into renal pelvis and ureter, no statistical difference was identified.