Mucin-producing urothelial-type adenocarcinoma of the prostate with sarcomatoid features and novel molecular phenotype.

Introduction: Mucin-producing urothelial-type adenocarcinoma of the prostate is a rare tumor that may not elevate serum prostate-specific antigen, creating significant diagnostic and monitoring challenges. We evaluate our case in detail and review prior studies to demonstrate that the pathologic and molecular features of this tumor are distinct from conventional prostate adenocarcinoma. Case presentation: Our patient had a remote history of radiation-treated conventional prostate adenocarcinoma and presented many years later with an abscess-like prostate mass leading to urinary obstruction and hematuria. Biopsy revealed mucin-producing urothelial-type adenocarcinoma of the prostate with concurrent sarcomatoid features. Molecular studies showed a unique phenotype involving alterations in the KRAS, PTEN, RAD21, and TP53 genes. Conclusions: To our knowledge, this is the first report that describes sarcomatoid features and molecular mutations in mucin-producing urothelial-type adenocarcinoma of the prostate.