Leydig cell hyperplasia in the setting of Klinefelter syndrome.

A man in his 20's with Klinefelter syndrome presented to the urology clinic with a recent history of left-sided orchalgia. Ultrasound evaluation demonstrated multiple small hypoechoic lesions bilaterally, with the largest lesion measured at 5 mm × 6 mm × 8 mm. Testis cancer tumour markers, chest radiographs and abdominal CT imaging were negative. A partial orchiectomy was performed on the largest lesion, demonstrating the presence of Leydig cell hyperplasia.