Malignant Leydig Cell Tumor

**Semantic type:** Neoplastic Process

**Definition:** A Leydig cell tumor characterized by large tumor size, the presence of cytologic atypia, increased mitotic activity, necrosis, and vascular invasion. Approximately 10% of the testicular Leydig cell tumors show malignant characteristics and metastasize. Leydig cell tumors of the ovary follow a benign clinical course.

**Synonyms:** - Carcinoma, Leydig Cell - Interstitial cell tumor, malignant - LEYDIG CELL TUMOR, MALIGNANT - Leydig cell tumor, malignant - Malignant Interstitial Cell Neoplasm - Malignant Interstitial Cell Neoplasm - Malignant Interstitial Cell Tumor - Malignant Interstitial Cell Tumor - Malignant Leydig Cell Neoplasm - Malignant Leydig Cell Neoplasm