Histological Description: The testis shows sheets of cytologically benign Leydig cells in the testis. These sheets are not only in the 1 cm lesion but in smaller foci scattered throughout the testis. Leydig cells are seen extending around nerves and rete testis in the hilum of the testis.
Answer: C

Discussion: The distinction between a benign Leydig cell tumor and Leydig cell hyperplasia is based on whether there is a solitary Leydig cell nodule with decreased or normal Leydig cells in the surrounding testis or there are multiple Leydig cell nodules of various size in the testis. In the latter setting, even in the presence of a fairly large nodule, the diagnosis is multinodular Leydig cell hyperplasia with a dominant nodule. It is analogous to the thyroid with the distinction of a follicular adenoma versus a dominant adenomatoid nodule in multinodular hyperplasia. In the current case, the outside contributor’s diagnosis of a Leydig cell tumor along with Leydig cells surrounding nerves in the hilum led to the consideration of a malignant Leydig cell tumor. It is a normal finding for Leydig cells to be situated around nerves in the hilum and when there is Leydig cell hyperplasia, the Leydig cells surrounding nerves can be hyperplastic as well. Multinodular Leydig cell hyperplasia can be seen in cryptorchid testes or pituitary conditions leading to a rise in luteinizing hormone or gonadotropin releasing hormone or impaired adrenal steroidogenesis. In adrenogenital syndrome, bilateral testes can be massively enlarged mimicking tumors due to marked Leydig cell hyperplasia. A misdiagnosis of Leydig cell tumors can result in bilateral orchiectomy as opposed to correcting the enzyme deficiency.