ODP278 A rare case of Ectopic ACTH secretion associated with Primary Gastric Choriocarcinoma

BACKGROUND: Ectopic ACTH production contributes to 10-15% of cases of Cushing's syndrome. Most cases are caused by neuroendocrine tumors of the lung, pancreas, or thymus. Other rare tumors causing ectopic ACTH secretion include esophageal tumor, gastric carcinoid tumor and squamous cell carcinoma of the larynx (1). We present a rare case of ectopic ACTH production causing Cushing syndrome due to primary gastric choriocarcinoma. CASE PRESENTATION: A 27-year-old lady, not known to have any chronic illnesses, presented with two days history of epigastric pain. The patient also reported facial puffiness, leg swelling, generalized weakness and oligomenorrhea for the last four months. There was no history of easy bruisability or weight. She was not taking any medications. The patient did not smoke or use alcohol. Physical examination revealed conjunctival pallor, facial acne, wide striae on her thighs and hepatomegaly. The rest of the examination was normal. Lab tests showed microcytic anemia with hemoglobin of 7 gm/dl (12-15 gm/dl), hypokalemia (2.5 mmol/L; normal 3.5-5.3 mmol/L), AST 38 U/L (0-40 U/L) and ALT 45 U/L (0-41 U/L). β HCG was 1,506 mIU/mL (0 -5 mIU/ml). An abdominal ultrasound showed hepatomegaly with multiple echogenic solid mass lesions suspicious of metastatic origin. A CT abdomen showed a solid lesion in the fundal region of the stomach with multiple liver metastases and moderate ascites. An esophagogastroduodenoscopy showed fungating mass originating from the stomach fundus. Biopsy of the gastric mass revealed primary gastric adenocarcinoma, which was positive forCK 7, CK 19, beta hCG, CDX2 and CEA, consistent with the diagnosis of primary gastric choriocarcinoma. Due to widespread metastasis, the patient was started on palliative chemotherapy with dexamethasone 2 mg injection once daily along with capecitabine, cisplatin and pembrolizumab. In view of persistent hypokalemia and physical examination findings, a workup for Cushing's syndrome was performed. Early-morning serum cortisol was 1054 nmol/L (138–689 nmol/L), and plasma ACTH was 174 pg/ml (7.2-63.3 pg/ml) despite the patient being on intravenous 2 mg dexamethasone once daily for more than ten days. An MRI of the brain showed a normal pituitary gland. Based on these findings, the patient was diagnosed with Cushing's syndrome due to ectopic ACTH secretion. Unfortunately, her hospital course was complicated by massive upper gastrointestinal bleeding from the tumor, leading to her demise. CONCLUSION: Gastric choriocarcinoma is a rare tumor associated with ectopic ACTH secretion leading to Cushing's syndrome. Reference: Imura H, Matsukura S, Yamamoto H, Hirata Y, Nakai Y. Studies on ectopic ACTH-producing tumors. II. Clinical and biochemical features of 30 cases. Cancer. 1975 May;35(5): 1430-7 Presentation: No date and time listed