[Torsion of the undescended testicle: a case report].

A 15-year-old boy was consulted to our hospital with the complaint of swelling of the left inguinal region with tenderness. Under the diagnosis of torsion of the undescended testicle, left orchidopexy was done with the finding of left testicle which had 360 degree counterclockwise intravaginal rotation. This was thought to be the 54th case of the disease in Japan. We have made some discussion on incidence, complication, diagnosis and therapy.