New insights into the expression of androgen and estrogen receptors of the appendix testis in congenital cryptorchidism.

Background: The appendix testis (AT) is the most common vestigial remnant of the human testis. Variations in the presence and expression of AT androgen receptor (AR) and estrogen receptor (ER) have been reported in cryptorchidism. We studied the possible association of AR and ER expression of the AT with cryptorchidism. Methods: ATs were resected from 40 boys who underwent inguinoscrotal surgery, (20 patients with congenital unilateral cryptorchidism [UC] and 20 controls with orthotopic testes and hydrocele). AR and ER expression was evaluated with immunohistochemistry, and the percentage and intensity of AR and ER expression were evaluated by the Allred scoring method. AT length was compared between the two groups. Correlation of AR and ER expression was evaluated independently in patients and controls. Results: The Allred score for AR trended toward lower values in UC compared to controls (p = 0.193), while ER scores presented statistically significant lower values in UC compared to controls (p = 0.017). No significant difference or trend was found in the expression of both receptors between high and low cryptorchidism (p = 0.981 for AR, p = 0.824 for ER) and for the appendiceal length between UC and controls (p = 0.369). Conclusions: The findings of a trend for lower AR expression and a statistically significant lower expression of ER in UC may suggest an association of AR and ER with cryptorchidism and may provide an insight into the process of testicular descent.