Rapidly growing immature retroperitoneal teratoma in a neonate

Abstract

Abstract Benign retroperitoneal teratomas are relatively rare tumors that usually progress slowly and are found in newborns and young adults. Here, we report a case in which a prenatally diagnosed retroperitoneal tumor rapidly increased in diameter from 55 mm to 90 mm during the neonatal period. The tumor was removed while preserving the surrounding organs. Moreover, the patient s postoperative course was uneventful. Pathological examination revealed an immature teratoma with no malignant findings. Notably, even benign neonatal teratomas may exhibit rapid growth of their cystic components after birth.