Leydig cell tumors of the testis.

Leydig cell tumors represent approximately one to three percent of all testicular tumors. Whereas in experimental animals predisposing conditions include administration of chemical carcinogens, hormones and heavy metals, environmental or endogenous factors in man are presently unrecognized. Leydig cell tumors do not show preferential lateralization or tendency for bilaterality. The symptoms are related to the local effects or to hormones released into the systemic circulation. Laboratory findings are variable, depending on endocrinological activity. Typical tumors rarely exceed five cm in diameter, are brown on cross section and are composed of polyhedral cells with acidophilic, granular cytoplasm. Ultrastructurally, neoplastic Leydig cells resemble normal Leydig cells. Surgical ablation is curative for benign Leydig cell tumors.