Abstract Disclosure: N. Anwaar: None. Adrenocortical carcinomas are rare and frequently aggressive tumors that may be functional (hormone secreting) and cause Cushing's syndrome and/or virilization or nonfunctional and present as an abdominal mass or as an incidental finding. We report a case of a 72-year-old lady who was presented to the ER with chest pain and elevated blood pressure. CTA was performed to evaluate for aortic dissection, which incidentally found a 5.0 x 3.7 cm right-sided adrenal mass. 1 mg overnight dexamethasone suppression study showed non-suppression of cortisol. The ACTH was suppressed, consistent with the autonomous production of cortisol from the adrenal gland. CT abdomen with adrenal protocol showed an indeterminate suspicious 5.1 x 3.9 cm right-sided adrenal mass. She underwent an adrenalectomy and the final pathology showed adrenocortical carcinoma. Postoperatively she was treated with adjuvant radiotherapy and chemotherapy. A few years later, she developed metastatic lesions and overt Cushing syndrome. She was started on pembrolizumab, which was later discontinued due to poor response and then placed on mitotane. The metastatic disease progressed, and the patient was transitioned to hospice care. Due to tumor’s rarity, the understanding and experience of management modalities are limited. New treatment options may be available in the coming years. Presentation: 6/1/2024