Right testicular necrosis and left vanishing testis in a neonate.

We describe a rare case of right testicular necrosis and left vanishing testis in a neonate. The patient presented with a right swollen testis and left non-palpable testis at birth. Exploratory laparotomy was performed at 23 days after birth, and the right testis was extirpated because of extensive necrosis due to torsion of the spermatic cord. Histopathological examination revealed a massively necrotic testicular structure with hypertrophy of Leydig cells. Hypergonadotropinemia was also recognized before operation. On laparoscopy at the age of 5.3 years, a normal left vas deferens and spermatic vessels exiting through the internal inguinal ring were confirmed, although the patient's left testis was not found in the intraperitoneal cavity. An hCG test demonstrated no response of serum testosterone. These findings suggested a diagnosis of left vanishing testis due to testicular regression. We therefore speculated that bilateral asynchronous testicular torsion had occurred prenatally in this patient.