Neuroendocrine tumor arising in an anterior mediastinal mature teratoma: A case report

Abstract Background: Mature teratomas are benign germ cell tumors. However, rarely they are associated with somatic malignancies, and are termed as rare germ cell tumors with a somatic type malignancy (GCTSM). Mature teratomas commonly comprise adenocarcinomas; only seven previous cases of mature teratomas with neuroendocrine tumors have been reported thus far. We report a case of mature teratoma with a neuroendocrine tumor.Case presentation: A 26-year-old man presented with a complaint of chest tightness. Contrast-enhanced computed tomography (CT) revealed a strongly enhanced lesion within a 10-cm encapsulated cystic lesion in the anterior mediastinum. Positron emission tomography (PET) revealed no areas of significant 18F-fluorodeoxyglucose (18F-FDG) accumulation. He underwent complete tumor resection via the transsternal approach. Histopathological examination of the specimen revealed a mature teratoma with a neuroendocrine tumor.Conclusions: Patients with a mature teratoma with a neuroendocrine tumor had no specific symptoms and serum markers were within the normal range. Although PET was beneficial for the diagnosis of other GCTSM, it was not useful for detecting a neuroendocrine tumor. Therefore, the preoperative diagnosis of mature teratomas with neuroendocrine tumors is difficult. However, GCTSM should be suspected in cases exhibiting CT findings of a mediastinal tumor, measuring 6 cm or greater, along with the characteristic findings of GCTSM. Moreover, surgery should be performed more carefully.