title: Transdifferentiation of Small Cell Carcinoma of the Urinary Bladder from Urothelial Carcinoma after Transurethral Resection of a Bladder Tumor, Intravesical Bacillus Calmette-Guerin Instillation, and Chemotherapy: A Case Report.
abstract: A 73-year-old male underwent transurethral resection of a bladder tumor in August 2010 and April 2011. Pathological examination revealed urothelial carcinoma. After the surgery, chemotherapy and intravesical Bacillus Calmette-Guerin instillation were performed. In September 2014, he once again underwent transurethral resection of the bladder tumor for recurrence, and was again diagnosed with urothelial carcinoma, pT2, by pathological examination. After neoadjuvant chemotherapy, radical cystectomy for tumor recurrence was performed. Pathological examination at this time revealed small cell carcinoma, pT3N0. It is rare for urothelial carcinoma to change to small cell carcinoma, and the mechanism and cause of this change are still unknown. In this case report, we discuss what causes small cell carcinoma of the urinary bladder and review the literature regarding its origin.
authors.affiliation: Department of Urology, Japan Community Health Care Organization Sendai Hospital, Sendai, Japan.
authors.forename: Kento
authors.initials: K
authors.lastname: Morozumi
authors.affiliation: Department of Urology, Japan Community Health Care Organization Sendai Hospital, Sendai, Japan.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Namiki
authors.affiliation: Department of Urology, Japan Community Health Care Organization Sendai Hospital, Sendai, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kudo
authors.affiliation: Department of Urology, Japan Community Health Care Organization Sendai Hospital, Sendai, Japan.
authors.forename: Masataka
authors.initials: M
authors.lastname: Aizawa
authors.affiliation: Department of Urology, Japan Community Health Care Organization Sendai Hospital, Sendai, Japan.
authors.forename: Naomasa
authors.initials: N
authors.lastname: Ioritani
authors.affiliation: Department of Pathology, Osaki Citizen Hospital, Osaki, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Sakamoto
authors.affiliation: Division of Pathology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Nakamura
keywords: Bacillus Calmette-Guerin; Chemotherapy; Small cell carcinoma; Transdifferentiation; Urinary bladder