ODP024 Adrenocortical Carcinoma Identified in a Patient With Familial Adenomatous Polyposis Syndrome

BACKGROUND: Numerous extracolonic manifestations are associated with familial adenomatous polyposis (FAP), including benign thyroid and adrenal nodules, less commonly thyroid and adrenal cancers. We describe a case of a patient with history of FAP who was found to have malignant lesions both in the thyroid and adrenal glands. CLINICAL CASE: A 54 year-old female with familial adenomatous polyposis (FAP) underwent partial colectomy at age 16. Known extracolonic manifestation at initial presentation was limited to a dermoid tumor of the right breast. Upon evaluation by endocrinology, she was found to have a dominant thyroid nodule in the right lobe that eventually doubled in size and was positive for papillary thyroid cancer with a BRAF V600E mutation. Successful total thyroidectomy with central neck lymph node dissection was completed, and she is now undergoing routine surveillance for ATA low risk PTC. She maintained annual endoscopic surveillance with gastroenterology and underwent serial abdominal imaging studies for complaints of abdominal discomfort. Right adrenal adenoma was first identified in August 2017 and screening for functionality, to include pheochromocytoma, was negative. Repeat abdominal imaging in 2020 showed the lesion increased in size by 30%. CT imaging identified the nodule as indeterminate based on the washout characteristics (HU 27 pre-contrast, absolute washout = 13% and relative washout = 8%). A 2cm left adrenal mass was also noted with radiographic features consistent with a lipid poor, benign, adenoma (HU 33 pre-contrast, absolute washout = 58%, relative washout = 39%). PET-CT was performed to further characterize the right sided lesion, which was vividly FDG avid at 8.7 SUV (high probability of malignancy). The left adrenal nodule was mildly FDG avid with an SUV of 2.4. CT-guided biopsy of the right adrenal gland was performed and immunohistochemistry did not stain for chromogranin, inhibin, pankeratin or calretinin. Positive staining for MART-1 was seen, which is a typically associated with adrenal cortical cells. There was a high index of suspicion for malignancy given her hereditary cancer syndrome, and the decision was made to proceed with right adrenalectomy. Final surgical pathology confirmed a low grade adrenocortical carcinoma with two nodular lesions, both staining CD10 positive with the mitotic marker (Ki-67) 2-3% positive. The patient's left adrenal gland remains functionally intact, and there were no indications to pursue postoperative treatment or adjuvant therapy. CONCLUSION: The patient presented here is representative of incidentally discovered nonfunctional adrenocortical carcinoma in the setting of a hereditary cancer syndrome. The available literature suggests that adrenocortical tumors should be considered FAP tumors, and sporadic mutations leading to adrenocortical carcinoma are less likely related to germline APC gene mutations Presentation: No date and time listed