1. Cryptorchidism affects 1% of 1-year-old boys.
2. It is the failure of descent and testes may be found anywhere along the normal path of descent, from abdominal cavity to the inguinal canal.
3. Most cases are idiopathic; other causes include:
i) Genetic abnormalities (e.g., trisomy 13)
ii) Hormonal abnormalities
4. Most cases are unilateral; 25% are bilateral.
5. Microscopically, the changes may be apparent, as early as 2 years of age, including decreased germ cell development, thickening and hyalinization of seminiferous tubular basement membrane, interstitial fibrosis, and relative sparing of Leydig cells. Spermatogenesis is lacking but Sertoli cells fill the lumen of the seminiferous tubules (Fig 19-3). Regressive changes may also occur in the contralateral descended testis.
6. Clinically, cryptorchidism is asymptomatic and it is found only when the scrotal sac is discovered not to contain the testis. Its significance is related to high prevalence of inguinal hernia, sterility, and a 5- to-10-fold increased incidence of testicular neoplasms.
Surgical correction (orchiopexy) decreases the likelihood of sterility, if performed early but does not decrease the risk of neoplasia, which may occur in either testis.