MON-352 Feminizing Adrenal Adenoma in an Adult Man Presenting with Gynecomastia and Hypogonadism

Abstract

Introduction: Feminizing adrenal tumors (FAT) are a rare cause of gynecomastia and hypogonadism in men. Most FATs are malignant and secrete other adrenal hormones and precursors. Rarely, benign adenomas solely secreting estrogens have been described. We present a patient with an estrogen-secreting adrenal adenoma with benign histology without secretion of other hormones or precursors. Case: A 43-year-old man presented with complaints of fatigue and erectile dysfunction for 24 months and painful bilateral breast growth for 12 months. Mammography revealed bilateral gynecomastia, and he was initially treated with tadalafil for erectile dysfunction. Due to persistent symptoms, labs were obtained revealing a low total testosterone level of 56 ng/dL (250-827 ng/dL). Further labs were obtained after an endocrinology evaluation: total testosterone 28 ng/dL, estradiol 44 pg/mL (≤29 pg/mL), estrone 192 pg/mL (≤68 pg/mL), estriol <0.10 ng/mL, FSH 0.8 mIU/mL (1.6-8.0 mIU/mL), and LH 3.1 mIU/mL (1.5-9.3 mIU/mL). Serum prolactin, β-hCG, AFP, ACTH, TSH and IGF-1 were all within normal ranges. Testicular ultrasound showed a left-sided varicocele. Adrenal protocol CT showed a 2.8 cm left adrenal nodule with characteristics of an adenoma (round, homogenous, pre-contrast Hounsfield units: 10, absolute washout: 68%). DHEAS, androstenedione, 11-deoxycortisol, 17-hydroxprogesterone, renin and aldosterone were all within normal ranges. 24-hour urine for cortisol, metanephrines and 17-ketosteroids were normal. He underwent laparoscopic left adrenalectomy. Pathology revealed a 2.5 cm well-circumscribed adrenal adenoma. Features favoring a benign histology included <1 mitotic figure/50 HPF, no atypical mitotic figures, no necrosis, and no capsular invasion. Repeat hormonal workup after surgery showed total testosterone 223 ng/dL, free testosterone 58 pg/mL (35-155 pg/mL), estradiol 16 pg/mL, estrone 39 pg/mL, and FSH 3.3 mIU/mL. On follow-up, the patient reported improvement in fatigue, decreased breast tenderness, and a slight decrease in breast size. Discussion: FATs most commonly present with painful gynecomastia and hypogonadism in males. Cosecretion of other adrenal hormones or precursors is suggestive of malignancy. Most FATs are malignant, and benign adenomas solely secreting estrogen are extraordinarily rare. Unfortunately, a benign appearance on histology may not predict a benign course. A case was previously reported with a young male child with FAT and initial benign histology, who later developed malignant metastases several years after the initial surgery. This demonstrates the importance of post-operative surveillance with imaging and serial hormonal evaluations.