Histological Examination of Solitary Contralateral Descended Testis in Congenital Absence of Testis

Purpose: Congenital absence of the testis is believed to be secondary to prenatal torsion, differing from the isolated undescended testis. We determined whether congenital absence of the testis is associated with abnormal histology in the solitary contralateral descended testis. Materials and Methods: A total of 239 boys with a primary diagnosis of unilateral absent testis underwent orchiectomy and testis biopsy. Germ cell counts were compared between solitary contralateral descended testes and contralateral descended testes in a randomly selected, age matched cohort of patients with unilateral undescended testes. Subanalyses evaluating hypertrophic testes and hypertrophic prepubertal testes between the study groups were performed. Results: The solitary contralateral descended testis group exhibited a significantly greater volume (p <0.001) and a significantly greater germ cell count (p = 0.001). In the hypertrophied testes there was a greater gonocyte count (p = 0.02), greater percentage of gonocytes (p = 0.02), greater primary spermatocyte count (p = 0.04) and greater percentage of primary spermatocytes (p = 0.03). No significant differences in adult dark spermatogonia or Leydig cells were detected. Primary spermatocytes did not differ significantly in prepubertal patients. Conclusions: The solitary contralateral descended testis exhibits increased volume, increased germ cell proliferation and dissimilar maturation patterns compared to the contralateral descended testis in unilateral cryptorchidism. These findings support prenatal torsion rather than endocrinopathy as the etiology for the congenitally absent testis. In the postpubertal solitary contralateral descended testis more germ cell maturation is seen and primary spermatocytes account for the increased total germ cell count. Patients with a solitary testis are likely not at additional risk for infertility.