Sex cord-stromal tumors of the testis

Abstract

Testicular tumors apart from those in the germ cell family are uncommon and are mostly sex cord-stromal tumors and may pose a major diagnostic challenge. This review focuses on the clinicopathologic features of these uncommon neoplasms, pertinent differential diagnoses, relevant immunohistochemical and molecular findings as well as the recent updates proposed by the World Health Organization (WHO). Contrast between these neoplasms as seen in the male and female gonad will also be made when warranted. The commonest sex cord-stromal tumor of the testis is the Leydig cell tumor which, when seen in children, is often associated with sexual precocity. The histologic features are generally those of an easily recognized oxyphilic neoplasm but various peculiarities such as microcysts and spindling of the tumor cells may case diagnostic difficulty on occasion. In the male, in contrast to the female, the most common sex cord-stromal tumor of epithelial nature is the Sertoli cell tumor. Most of these fall in the not otherwise specified category and are usually characterized by a diagnostically helpful at least focal hollow or solid tubular pattern. Occasional malignant Sertoli cell tumors have a predominantly diffuse pattern sometimes interrupted by septa with a lymphocytic infiltrate that can cause seminoma to be mimicked. Rare Sertoli cell tumors are associated with marked sclerosis. The so-called large cell calcifying Sertoli cell tumor, may be sporadic or associated with manifestations of the Carney syndrome. A distinctive entity referred to as intratubular hyalinizing Sertoli cell neoplasia occurs in the testis of young boys with Peutz-Jeghers syndrome. It is often bilateral, microscopic and associated with gynecomastia. Testicular granulosa cell tumors are much rarer than their ovarian counterparts but can be similarly subdivided into adult and juvenile forms. In the male, the juvenile granulosa cell tumor has a particularly striking tendency to occur in the first 6 months of life. The primitive appearance of the nuclei and brisk mitotic activity of the juvenile granulosa cell tumor may result in a misdiagnosis of a more malignant neoplasm. The histologic spectrum of the adult granulosa cell tumor is as seen in the more common female examples. Pure stromal tumors of the testis are much less common than similar tumors in the ovary and the well-known thecoma is remarkably rare in the testis. Fibromas of stromal derivation in the testis should be distinguished from fibromas that originate from the tunica albuginea and from examples of the non-neoplastic process nodular pseudotumor.