Hypochromatic large urothelial cells in urine cytology are indicative of high grade urothelial carcinoma

Abstract

In this study, we have examined 67 cytology specimens from patients from 2014 to 2016. The ratio man to women was 4:1 with a median age of 75 years (range: 55-87 years). Thin-Prep processed urinary cytology specimens demonstrated large urothelial cells, with cytologic features of malignancy, thus including hypochromatic nuclei with occasional peripherally accentuated chromatin rim. The cytological diagnosis of High Grade Urothelial Carcinoma (HGUC) was made in 55 patients while 12 specimens were classified as Atypical Urothelial Cells (AUC). This cases represent the 15% of the HGUC and the 4% of the AUC cases diagnosed in our department between 2016 to 2018. Of note, is the fact that in AUC cases, hypochromatic irregular urothelial cells were the only type of cells with malignant features observed in the specimen, and therefore, according to the Paris System criteria, the absence of nuclear hyperchromasia precludes a diagnosis of suspicious high grade urothelial carcinoma (SHGUC) or High Grade Urothelial Carcinoma (HGUC). Subsequent biopsy diagnosis of high grade urothelial carcinoma confirmed the cytological diagnosis of HGUC in 55 patients but also in all 12 patients with a AUC cytologic diagnosis. Our study series support the hypothesis that malignant urothelial cells with hypochromatic nuclei seen in urine cytologic specimens can be diagnostic for HGUC based on their very large nuclei, high nuclear cytoplasmatic ratio (N/C) >0.7, irregular nuclear outlines and coarse (frequently peripheral) chromatin in the absence of hyperchromasia.

Keywords: Paris system for reporting urinary cytology; atypical urothelial cell; hypochromatic nucleus; urothelial carcinoma.