Diagnosis of an indistinct Leydig cell tumor by positron emission tomography-computed tomography.

A 51-year-old perimenopausal female patient presented with hirsutism and voice thickening which was started approximately one and a half years ago. Her initial hormone assay revealed elevated plasma testosterone, 5a-dihydrotestosterone, and dehydroepiandrosterone (DHEA) levels and therefore androgen-secreting tumor was first suspected. However, the lesion was inconspicuous on transvaginal sonography, abdominal-pelvic computed tomography (CT) scan, and pelvic magnetic resonance (MRI) imaging. Consequently, 18F-fluorodeoxyglucose (FDG) positron emission tomography-CT was performed, which localized the lesion as a focal FDG uptake within the right adnexa. Total laparoscopic hysterectomy with bilateral salpingo-oophorectomy was performed, and although visible gross mass lesions were not observed intraoperatively, pure Leydig cell tumor was pathologically confirmed within the right ovary. Plasma testosterone, 5a-dihydrotestosterone, and DHEA levels were normalized postoperatively. Clinical signs of virilization were also significantly resolved after 3-months of follow-up.