increased testis tumor incidence increased Leydig cell tumor incidence Leydig cell tumour MP:0009592 MPheno.ontology interstitial cell tumour of testis increased Leydig cell tumour incidence greater than the expected number of rare testicular tumors of the male gonadal interstitium, occurring in a specific population in a given time period; Leydig cell tumors are frequently hormonally active, leading to feminizing or virilizing syndromes; Leydig cell tumors comprise 1-3% of all testicular neoplasms, can be pure or mixed with other sex cord-stromal or germ cell tumors, and are usually benign, although malignant variants also occur interstitial cell tumor of testis Leydig cell tumor