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Int J Clin Exp Pathol 2013;6(11):2578-2584

Case Report
Concurrent primary carcinoid tumor arising within mature teratoma and clear cell renal
cell carcinoma in the horseshoe kidney: report of a rare case and review of the literature

Ke Sun, Qihan You, Ming Zhao, Hongtian Yao, Hua Xiang, Lijun Wang

Department of Pathology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, China;
Department of Pathology, Ningbo Yinzhou Second Hospital, Ningbo, Zhejiang 315100, China

Received August 16, 2013; Accepted September 20, 2013; Epub October 15, 2013; Published November 1, 2013

Abstract: Primary carcinoid tumor arising in a mature teratoma of the horseshoe kidney is exceptionally rare and only 4 such cases have been
reported in the world literature to date. The simultaneous occurrence of different subtypes of renal cell carcinoma (RCC) or RCC coexistence
with non-RCC neoplasms from the same kidney is unusual and infrequently reported. Herein we report a case of primary carcinoid tumor
arising within mature teratoma, concurrent with a clear cell RCC in the horseshoe kidney of a 37-year-old man. Histologically, both the
carcinoid tumor and clear cell RCC demonstrated the characteristic morphology in their classic forms. In addition to the carcinoid tumor, the
mature teratoma consisted of variably sized, large cystic spaces lined by cytologically bland mucinous columnar epithelium, pseudostratified
columnar epithelium, ciliated epithelium and mature smooth muscle fibers were also identified within the cystic wall. Furthermore, foci of
round, small nodules composed of mature prostatic acinus were noted in the teratoma which was confirmed by exhibiting strong
immunoreactivity for prostate specific antigen. The present case serves to expand the histologic component that may be encountered in the
mature terotoma of the kidney and further broadens the spectrum of primary tumors occurring in the horseshoe kidney. (IJCEP1308045).

Keywords: Kidney, carcinoid tumor, mature teratoma, horseshoe kidney, prostate tissue

Address correspondence to: Dr. Lijun Wang, Department of Pathology, The First Affiliated Hospital, College of Medicine, Zhejiang University,
No.79 Qingchun Road, Hangzhou, Zhejiang 310003, China. Tel: +86-571-87236364; Fax: +86-571-87236364; E-mail: Wanglj6368@gmail.com