Figure 13a.

Leydig cell neoplasm in a 24-year-old man with a palpable right scrotal mass and new-onset gynecomastia. (a, b) Gray-scale US (a) and color Doppler (b) images of the right testis show a well-circumscribed hypoechoic mass (arrow in a) with internal color flow (arrow in b). (c, d) Photograph of the gross pathology specimen (c) and high-power photomicrograph (d) show a well-circumscribed mahogany brown mass (arrow in c) and polygonal cells with abundant eosinophilic cytoplasm (black arrows in d) and prominent nucleoli (white arrows in d), characteristic of Leydig cell tumor. (H-E stain.)