Introduction: Leydig cell tumors may generate estrogen production and gynecomastia.
Case presented: A 32-year man asked for medical advice due to gynecomastia. He had raised estrogen levels and diminished testosterone/estradiol index. A testicular echogram showed a nodular image in the right testis. Orchidectomy was performed and the diagnosis of a Leydig cell tumor was confirmed. The gynecomastia diminished, and estradiol remained lightly elevated, with little response to HCG.
Discussion: The more frequent hormonal manifestations of these tumors are high plasmatic and urinary estrogen levels, low serum testosterone, low testosterone/estradiol index, and FSH or LH low levels as well. The low response to HCG, the absence of metastasis and the good clinical evolution suggested the tumor was benign. Testicular echography is useful in the diagnosis of these tumors.