Significance of Denuded Urothelium in Papillary Urothelial Lesions

Abstract

Flat urothelial carcinoma in situ (CIS) is often characterized by prominent dyscohesion with some cases having only a few clinging CIS cells remaining on biopsy. The finding of extensive denudation on urothelial biopsies is associated with a risk of CIS on either prior or subsequent biopsies. The significance of denudation in papillary urothelial lesions has not been formally studied. We identified from our surgical pathology files 31 specimens (from 28 patients) of papillary urothelial lesions with extensive denudation. In cases in which denudation was associated with low-grade urothelial neoplasms, follow-up of subsequent cytologic and histologic specimens was obtained. Of the 28 patients, 25 (89%) were men and 3 (11%) were women with an age range of 40 to 88 years old (mean age 62). Of 31 biopsies, 15 were from anatomically confined areas (ie, renal pelvis, ureter, and urethra). In 22/28 (79%) patients, prominent denudation was associated with high-grade papillary carcinomas, 4/28 (14%) low-grade papillary carcinomas, and 2/28 (7%) papillary urothelial neoplasms of low-grade malignant potential. The average extent of urothelial denudation was 82% with 61% of cases having > or =90% denudation. Prominent cautery artifact was present in 17/31 (55%) cases. In 13/28 patients with high-grade lesions, there was a concurrent biopsy of a second urothelial lesion that was either high-grade papillary urothelial carcinoma or invasive urothelial carcinoma. Five of the 6 patients in which the prominent denudation was associated with a low-grade papillary urothelial lesion have not progressed to a high-grade lesion. One patient with a denuded papillary urothelial neoplasm of low malignant neoplasm was subsequently diagnosed with a noninvasive low-grade papillary urothelial carcinoma in the bladder and a high-grade infiltrating urothelial carcinoma of the ureter. We conclude that (1) the majority of papillary urothelial lesions associated with prominent urothelial denudation are high grade; (2) a significant percentage of papillary urothelial lesions with denudation occur with either prominent cautery artifact or in anatomically confined areas, suggesting both iatrogenic and mechanical contributing factors, respectively; (3) a minority of cases with prominent urothelial denudation occur in association with low-grade papillary urothelial lesions and are not associated with progression to higher grade lesions on follow-up studies; and (4) prominent urothelial denudation in papillary lesions should prompt careful examination of these specimens for rare clinging high-grade carcinoma cells, although in a minority of cases the underlying lesion will be low grade.