Microscopic description:

Uretheritis cystica with chronic inflammation and reactive urothelial changes.

Mildly hyperplastic urothelium with an inflamed and markedly edematous stroma.

Ectatic blood vessels and polypoid with broad-based papillary structures are present in the urothelium.

Based on the histopathological features, the tumor shows features consistent with polypoid urethritis.

Discussion:

Polypoid urethritis is a subtype of polypoid cystitis that presents in the urethra.

Polypoid cystitis is a reversible, exophytic, inflammatory lesions of the urinary tract mucosa. They generally manifests as multiple small benign polypoid lesions.

There is no association between gender, age, or geographic location. However, about 80% of cases of polypoid cystitis occur in patients with prolonged catheterization (occurrence peaks at 3 months). Treatment includes removing the catheter/aggravating agent.

These lesions that are commonly mistaken for urothelial carcinoma. Polypoid cystitis can be histologically differentiated from papillary urothelial neoplasia by utilizing the low-powered field over the high-powered field.

Low-powered field: background is reactive, inflamed, and edematous. Simple, non-branching, broad-based fronds are present. Urothelium of normal thickness.

High-powered field: Exceptional fronds may resemble a urothelial neoplasm.

References:

Beeter MC, Yeh YA. Polypoid / papillary cystitis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/bladderpolypoidcystitis.html. Accessed September 19th, 2023.

Ekelund P, Johansson S. Polypoid cystitis: a catheter associated lesion of the human bladder. Acta Pathol Microbiol Scand A. 1979 May;87A(3):179-84. PMID: 380263.

Kryvenko ON, Epstein JI. Mimickers of urothelial neoplasia. Ann Diagn Pathol. 2019 Feb;38:11-19. doi: 10.1016/j.anndiagpath.2018.09.012. Epub 2018 Sep 26. PMID: 30380401.

Lane Z, Epstein JI. Polypoid/papillary cystitis: a series of 41 cases misdiagnosed as papillary urothelial neoplasia. Am J Surg Pathol. 2008 May;32(5):758-64. doi: 10.1097/PAS.0b013e31816092b5. PMID: 18379418.

Roh JE, Cho BS, Jeon MH, Kang MH, Lee SY, Song HG. Polypoid Cystitis in an Adult without History of Catheterization. Iran J Radiol. 2011 Nov;8(3):173-5. doi: 10.5812/kmp.iranjradiol.17351065.3145. Epub 2011 Nov 25. PMID: 23329937; PMCID: PMC3522325.

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