Leydig cell hyperplasia
 Discussion of Leydig cell hyperplasia
- Leydig cell hyperplasia is a rare, benign condition characterized by multiple small testicular nodules, frequently bilateral.
- Various conditions have been associated with Leydig cell hyperplasia, including cryptorchidism, congenital adrenal hyperplasia, human chorionic gonadotropin (hCG)–producing germ cell tumors, Klinefelter syndrome, and exogenous hCG therapy.
- When bilateral multifocal testicular masses are identified, the possibility of benign Leydig cell hyperplasia should be considered, as this gives the urologist the option of performing a surgical biopsy rather than orchiectomy to exclude malignancy.
- The differential diagnosis for multiple nodular lesions includes lymphoma, leukemia, metastatic disease, granulomatous disease, and bilateral primary testicular neoplasm.
 Imaging Findings for Leydig cell hyperplasia
- The sonographic appearance can be variable, with both hypoechoic and hyperechoic appearances having been described.
- At MR imaging, multiple small (1–6-mm) nodules are seen, which are hypointense on T2-weighted images. There may be mild enhancement after administration of gadolinium.
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 References for Leydig cell hyperplasia
- Woojin Kim, Mark A. Rosen, Jill E. Langer, Marc P. Banner, Evan S. Siegelman, and Parvati Ramchandani. US–MR Imaging Correlation in Pathologic Conditions of the Scrotum. RadioGraphics 2007 27: 1239-1253.