2019-6 / MARCH 25 (CONTRIBUTOR: JONATHAN EPSTEIN)
A 54 year old man presented with multiple bone metastases and a mass involving the bladder neck. A TUR of the bladder was performed. On outside stains, the tumor was negative for CD138, kappa and lambda light chains, CD56, CD45, CK7, HMWCK, AE1/3, desmin, and GATA3. Stains performed at our institution were positive for NKX3.1, P501S, PSA and negative for GATA3 and Uroplakin II. E-cadherin was lost in the tumor.
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What is the correct diagnosis?
a. Plasmacytoid urothelial carcinoma
b. Poorly differentiated prostatic adenocarcinoma with plasmacytoid features
c. Plasma cell tumor