Abstract Disclosure: S. Syed: None. Background: Pure androgen secreting adrenal adenomas are extremely rare; most of the reported cases occur in post-menopausal women, with significant virilization of acute onset and are usually malignant. Here we present a case of an androgen secreting adrenal adenoma found in a young female with regular menstrual cycles and hirsutism. Clinical Case: A 27-year-old female with no significant past medical history was referred to Endocrinology clinic for evaluation of elevated testosterone level noted on a routine OBGYN exam. Patient had miscarriage six months prior to initial endocrine clinic visit. She had a routine follow up visit with her gynecologist after miscarriage and noted to have mild male pattern hair growth on her chin, worse after stopping birth control pills two years ago. Patient had menarche at 14 years of age and had regular menstrual cycle until started birth control pills. The skin examination revealed coarse male pattern hair on chin. Scattered acne was present on back. No signs of hypercortisolism were present. Labs done at time of initial consultation showed unremarkable comprehensive metabolic panel, thyroid and gonadotropic hormones. Testosterone was elevated at 122ng/dl (0-75ng/dl). Pelvic ultrasound done in the year prior showed normal uterus and adnexal structures. Further work up showed elevated DHEAS 781 µg/dL (18-391 µg/dL) and normal 17 OH progesterone and androstenedione levels. MRI abdomen with and without contrast done at outside facility showed a 4 cm x 3.3 cm x 4.1 cm well-circumscribed round shaped, mildly heterogeneously enhancing mass arising from right adrenal gland, with restricting diffusion, no signal dropout in out-of-phase imaging. Normal ovaries were noted. Given the large size of lesion, adrenalectomy was recommended. Patient underwent laparoscopic right adrenalectomy. The histologic features on pathology specimen were consistent with an adrenal cortical adenoma. No evidence of malignancy was seen (based on modified Weiss criteria). 3 weeks post op labs showed Testosterone level reduced to 19 ng/dl (0-75ng/dl) and DHEAS 138 ug/dl (18-391 µg/dL). Patient is recovering from recent childbirth. Conclusion: In adults, pure androgen secreting adrenal tumors are extremely rare. Diagnosis of malignancy is made with histopathological examination and Weiss score calculation. Our patient has unique presentation of having mild hirsutism in setting of regular menstrual cycles with no other symptoms of virilization and is noted to have unexpectedly large adrenal adenoma. Given the size of adenoma, there was concern for adrenal cortical carcinoma, however histological examination was consistent with a benign lesion. Presentation: 6/1/2024