Malignancy in Leydig Cell Tumor
Malignancy in Leydig Cell Tumors (LCT): Almost 95% of LCT pursue a benign clinical course. Malignant behavior is more likely in adults and has not be reported before puberty. Gynecomastia is more commonly associated with benign tumors. Pathologic features associated with malignancy in LCT include: large size (> 5 cm), increased mitotic activity (> 3 mitoses/10 HPF), atypical mitotic figures, lympho-vascular invasion, infiltrative borders, extratesticular extension, necrosis, nuclear anaplasia, DNA aneuploidy, high Ki-67 labeling index, and p53 expression. However, it must be mentioned that these histologic criteria for malignancy in LCT are not consistently reliable. Rare cases (< 1%) with no pathologic risk factors of malignancy may still behave in a malignant fashion. The only definitive criterion for malignancy is the presence of metastasis. The image shows malignant LCT with highly anaplastic features.