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Int J Clin Exp Pathol 2013;6(6):1150-1156

Case Report
Urinary bladder urothelial carcinoma with expression of KIT and PDGFRA and showing
diverse differentiations into plasmacytoid, clear cell, acantholytic, nested, and spindle
variants, and into adenocarcinoma, signet-ring cell carcinoma, small cell carcinoma,
large cell carcinoma, and pleomorphic carcinoma

Tadashi Terada

Department of Pathology, Shizuoka City Shimizu Hospital, Shimizu, Shizuoka, Japan

Received March 2, 2013; Accepted March 23, 2013; Epub May 15, 2013; Published June 1, 2013

Abstract: Various tumors can arise in the urinary bladder (UB); most common is urothelial carcinoma (UC). UC of the UB have many variants.
Other types of carcinomas such as adenocarcinoma (AC) and small cell carcinoma (SmCC) can occur in UB carcinomas. Expression of KIT
and PDGFRA has not been reported. A 66-year-old man admitted to our hospital because of hematuria. Cystoscopy revealed papillary invasive
tumor and a transurethral bladder tumorectomy (TUR-BT) was performed. The TUR-BT showed UC, AC, SmCC, large cell carcinoma (LCC),
and pleomorphic carcinoma (PC). The UC component showed plasmacytoid, spindle, nested, clear cell, acantholytic variants. The AC element
showed tubular adenocarcinoma and signet-ring cell carcinoma (Sig). Immunohistochemically, all of these subtypes were positive for
cytokeratin (CK) AE1/3, CK CAM5.2, CK34BE12, CK5, CK6, CK7, CK8, CK18, CK19, CK20, EMA, CEA, p63, CA19-9, p53 (positive 45%), MUC1,
NSE, NCAM, KIT, PDGFRA, and Ki-67 (87%). They were negative for vimentin, chromogranin, synaptophysin, S100 protein, CD34, CD14, α-
smooth muscle actin, CD31, caldesmon, CD138, CD45, κ-chain, λ-chain, MUC2, MUC5AC and MUC6. Mucin histochemistry revealed mucins
in AC element including Sig. A molecular genetic analysis using PCR-direct sequencing method identified no mutations of KIT (exons 9, 11, 13,
and 17) and PDGFRA (exons 12 and 18) genes. The carcinoma was highly aggressive and invaded into muscular layer. The nuclear grade
was very high, and there were numerous lymphovascular permeations were seen. The surface showed carcinoma in situ involving von-Brunn’s
nests. This case shows that carcinoma of UB can show diverse differentiations into numerous histological types and variants, and can express
KIT and PDGFRA. The both genes showed no mutations in the present case. (IJCEP1303005).

Keywords: Urinary bladder, urothelial carcinoma, small cell carcinoma, adenocarcinoma, KIT, PDGFRA

Address correspondence to: Dr. Tadashi Terada, Department of Pathology, Shizuoka City Shimizu Hospital, Miyakami 1231 Shimizu-Ku,
Shizuoka 424-8636, Japan. Tel: 81-54-336-1111; Fax: 81-54-336-1315; E-mail: piyo0111jp@yahoo.co.jp