Picture1 Case5264 year old man with hematuria undergoes a TURP for urinary obstruction and bulky mass per digital rectal examination. Representative microphotographs of the resected tissue are shown. 

 What is the most likely diagnosis?

A. Prostatic adenocarcinoma.
B. Small cell carcinoma of the prostate.
C. Rhabdomyosarcoma.
D. Urothelial carcinoma.



 Picture3 Case52

Answer

The answer is D, urothelial carcinoma (with sarcomatoid differentiation).
The immunohistochemical stain is GATA3 supporting the diagnosis. Sarcomatoid urothelial carcinoma is uncommon and can be associated with diagnostic difficulty when encountered. As sarcomatoid urothelial carcinoma can show a broad range of morphologic appearances. This can raise the differential diagnosis of non–epithelial-derived tumors. Appropriate immunohistochemical stains are needed to exclude nonepithelial neoplasms in the differential diagnosis. The mean survival is poor (often less than 12 months), despite surgical intervention and chemotherapy. Contributing to this poor outcome was the advanced stage of disease at surgical resection, as well as the presence of subsequent distant metastases in a large proportion of patients.

Reference:
Sanfrancesco J, McKenney, J, et al. Sarcomatoid Urothelial Carcinoma of the Bladder Analysis of 28 Cases with Emphasis on Clinicopathologic Features and Markers of Epithelial-to-Mesenchymal Transition. Arch Pathol Lab Med. 2016;140:543–551.

 Contributed by Erik Kouba, M.D.