Twenty-nine Leydig cell tumors: histological features, outcomes and implications for management.

Leydig cell tumors are the most common interstitial neoplasm of the testes. Metastatic progression is historically quoted at over 10%, fuelling uncertainty as to the safety of testis sparing surgery. Between June 1998 and March 2009, 29 patients underwent surgery for Leydig cell tumor of the testis in our cancer network. We reviewed their histological features and clinical outcomes. Four patients with sub-5 millimetre lesions underwent testis sparing surgery and 25 were treated with radical orchidectomy. Histopathological characteristics that have been linked with risk of malignant progression were seen infrequently in our cohort: diameter greater than 50 mm, 0%; nuclear atypia, 14%; >3 mitoses per 10 high-power fields, 3%; infiltrative borders, 10%; necrosis, 3%; and vascular invasion 0%. No patient developed local or distant recurrent disease over a median follow up of 49 months, including seven and four patients disease-free at 5 and 10 years, respectively. The rate of metastatic progression is likely to be significantly less than 10%. Our data suggest that, in the absence of high-risk histopathological features, this tumor can be safely regarded as benign, pending a longer-term follow-up evaluation.