Testicular Regression Syndrome Presenting as a Nonpalpable Undescended Testis in Adulthood: A Case Report and Literature Review.

Vanishing testis is also known as testicular regression syndrome, which is atrophy and disappearance of one testis during fetal life. Vanishing testis accounts for < 5% of undescended testis. Vanishing testis is a rare condition that must be remembered in the differential diagnosis of undescended testis. We report a case of vanishing testis in a young man of 29 years old who underwent inguinal exploration for nonpalpable undescended testis. There was no obvious testis at exploration and instead the vas deferens together with cord vessels ended blindly distally. The spermatic cord was excised and the patient fared well postoperatively.