Gynecomastia and Leydigioma: An Unexpected Case Report Outcome

We report a case of a 19-year-old male referred to the Endocrine Unit because of gynecomastia. Initial investigation revealed elevated levels of estradiol (E2) along with secondary hypogonadism (hypotestosteronemia and severe oligoasthenoteratozoospermia (OAT)) despite normal testicular volume (12 mL) and secondary sexual characteristics. Surprisingly, an ultrasound examination revealed a small hypoechoic mass (1.1 cm) with intense intralesional vascularization within the right testicle, even though tumor markers were normal. Surgical removal of testicular mass led to the identification of Leydigioma, and the patient showed regression of gynecomastia during the nine-month follow-up. Unexpectedly, hypergonadotropinemia manifested along with normal testosterone (T) levels and significant improvement in OAT. Magnetic resonance imaging (MRI) showed pituitary hyperplasia (PH). Gynecomastia represents an atypical manifestation of Leydig cell tumors and typically resolves after surgical removal. However, unilateral orchiectomy may determine compensatory PH. Currently, it is uncertain whether the shift from hypogonadotropic to permanent hypergonadotropinemia was the only factor responsible for the high sperm count occurring in our patient. Further research is needed to elucidate the underlying mechanisms.