Nephroblastic elements in a retroperitoneal immature teratoma with elevated serum alpha-fetoprotein

Introduction: Teratoma and Wilms’ tumor are among the most frequent tumors of childhood. The occurrence of nephroblastic elements in a teratoma is extremely rare. Only eight cases that occurred in the retroperitoneum have been reported in English literature. Such occurrence complicates the differential diagnosis because of the overlapping histopathological findings between teratoma with nephroblastic elements and teratoid Wilms’ tumor. Alpha-fetoprotein (AFP) is a recognized marker of immature teratomas. The source of AFP is believed to be from gastrointestinal epithelium and neuroepithelium. To our knowledge, this is the first case of elevated serum AFP level observed in a retroperitoneal immature teratoma with nephroblastic elements. Case Report: A three and a half-month-old Taiwanese female infant presented with an abdominal distension. A retroperitoneal neoplasm was detected by the abdominal computed tomography scans. Chiu-Hsuan Cheng1, Shang-Hsien Yang2, Borcherng Su3 Affiliations: 1MBBS, Resident pathologist, Department of Pathology, Buddhist Tzu Chi General Hospital, Hualien city, Hualien county, Taiwan; 2MD, Attending pediatrician and pediatric hemato-oncologist, Department of Pediatric Hematology and Oncology, Buddhist Tzu Chi General Hospital, Hualien city, Hualien county, Taiwan, School of Medicine, Tzu Chi University, Hualien city, Hualien county, Taiwan; 3DDS, PhD, Attending pathologist, Department of Pathology, Buddhist Tzu Chi General Hospital, Hualien city, Hualien county, Taiwan, School of Medicine, Tzu Chi University, Hualien city, Hualien county, Taiwan. Corresponding Author: Borcherng Su, Complete Mailing Address No. 701, Section 3, Zhongyang road Hualien City, Hualien County, Taiwan, 970; Email: [email protected] Received: 09 May 2016 Accepted: 07 June 2016 Published: 05 July 2016 Histologically, nephroblastic elements in lobular contour were noted comprising about 15% per slide along with mixed elements of grade 3 teratoma in organoid arrangement. Her preoperative serum AFP level (1182 ng/ml) was above the physiologic level for her age. It decreased to 312.5 ng/ml at one week after tumor excision. She was well with no evidence of tumor recurrence at the age of one and a half years with unremarkable AFP blood level. Conclusion: We made the diagnosis of retroperitoneal immature teratoma with nephroblastic elements due to their preservation of lobular shape and organoid arrangement of mixed elements from different germ layers. A significant AFP level elevation may be noted in immature teratomas regardless of the presence of nephroblastic elements.