[Unilateral anorchidism or monorchidism].

Monorchidism is a Testicular Regression Syndrome (Vanishing Testis Syndrome), defined as the unilateral or bilateral partial and complete absence of testicular tissue with or without rudimentary epididymal and spermatic cord remnants in the presence of normal duct development and normal external genitalia. In this paper we report the results of a personal series of 36 patients. We discuss the histopathology and try to answer the question whether protection of the solitary contralateral testis by orchidopexy is necessary in monorchidism. Our results suggest that a fixation of the contralateral testis is not necessary in children operated on for monorchidism. The histopathological findings provide a support for the concept of in utero torsion of the testis as the basis for the Testicular Regression Syndrome. These findings are characteristic, if non-specific. Vas deferens, epididymis, calcification or hemosiderin pigmentation was noted in almost 90% of the cases. In the absence of these remnants clinical and surgical findings and the presence of a richly vascular stroma supported the diagnosis.