Abstract Disclosure: T.D. Bertolacini da Silva: None. V.D. Kamura: None. P.D. Buchalla: None. A.G. Simoes: None. S. Glina: None. Z.M. Campos: None. I.S. Rosa: None. P.X. Santi: None. Background: The association of dependent Cushing's ACTH Syndrome with certain types of cancer is well known, such as small cell lung cancer, enteropancreatic tumors, thymoma, thyroid cancer, however, in association with cervical cancer there are almost no cases described. Clinical Case: A 39-year women, showed about 2.5 years ago with abnormal uterine bleeding, being submitted to colposcopy with the presence of exophytic, friable and hardened lesion in the anterior region of the cervix. Biopsies revealed adenocarcinoma, endometrioid type and immunohistochemistry (IHC) positive for: Ki-67 80%, vimentin and CEA. Patient underwent initial treatment with chemotherapy and radiotherapy, losing follow-up with Oncology. After 1 year, the patient was admitted to a hospital with behavioral alteration, including suicidal ideation, muscle weakness, breast enlargement and hair growth on the face. On physical examination, there was the presence of hypertension, hyperglycemia, centripetal obesity, legs edema and hirsutism. Due to the typical symptoms, the hypothesis of Cushing's Syndrome was made and laboratory and imaging tests were requested. Initial tests: K 1.9 mmol/L (3.5-5.6 mmol/L), Na 146 mmol/L (137-145 mmol/L), TSH 0.25 uIU/mL (0.49-5.58 uIU/mL/mL), free T4 0.78 ng/dL (0.89-1.53 ng/dL), pH 7.57 (7.36-7.41), HCO3 43.1 mmol/L (23-27 mmol/L), LH 0.15 mIU/mL (1.9-12.5 mIU/mL), FSH 1.02 mIU/mL (2.5-10 mIU/mL), estradiol 84.1 pg/mL (< 32.2 pg/mL), ACTH 365.0 pg/mL and 98.6 pg/mL (< 46 pg/mL), cortisol > 75 ug/dL (5.27-22.5 ug/dL), urinary cortisol 3790 ug/24h (4-60 ug/24h), testosterone 333 ng/dL (12 - 59 ng/dL), free testosterone 10.12 ng/dL (0.08-1.1 ng/dL), dehydrotestosterone 1,620 pg/mL (< 596 pg/mL), androstenedione > 10 ng/mL (0.3-3.3 ng/mL). The dosages of ACTH and cortisol were performed after the dexamethasone suppression test and a pituitary MRI was normal. The MRI of the abdomen and pelvis showed multiple solid nodular lesions in liver with varying sizes compatible with metastatic disease, in addition, showed the increase in the bilateral volume of the adrenals. Liver biopsy was performed exhibiting carcinoma infiltration with IHC compatible with neuroendocrine tumor, positive for: CDX-2, SATB2, chromogranin A and synaptophysin (waiting for ACTH). Other primary sites were ruled out. The patient was initially treated with Etomidate in a continuous infusion, without tolerance and little control of hypercortisolism, after initiating Ketoconazole which was suspended due to hepatotoxicity, and then underwent bilateral adrenalectomy. Unfortunately, she died 4 days after surgery due to septic shock. Conclusion: This case report brings a very rare association of Cushing's syndrome by ectopic ACTH due to cervical cancer, with less than 10 cases reported, in which we highlight the diagnostic difficulty, the complexity of treatment and the high risk of morbidity and mortality. Presentation: 6/1/2024