MON-LB042 A Rare Case of Adrenocortical Carcinoma Arising From Ectopic Adrenal Tissue in the Mesentery

Background: ACTH independent Cushing’s syndrome usually arises from benign or malignant tumors of the adrenal gland. Ectopic adrenal tissue can undergo malignant transformation resulting in the development of adrenocortical carcinoma (ACC) with normal adrenal glands. We present a unique case of ACTH independent Cushing’s syndrome from a cortisol and androgen producing ACC arising from the mesentery. Clinical Case: A 72-year-old woman presented with a 6-month history of progressive weakness, lower extremity edema, worsening hypertension and uncontrolled DM. She had moon facies, hirsutism, multiple bruises, and proximal muscle weakness. Labs revealed hypokalemia (2.6 mmol/L, N 3.5 -5.1 nmol/L), elevated random cortisol (51.3 mcg/dL, Nl- 5-23), suppressed ACTH (<1 pg/mL, Nl-7.2-63.3) abnormal 8 mg dexamethasone suppression test (58.1 mcg/dL, N <1.8 mcg/dL), elevated DHEAS (538mcg/dL, N 10-90 mcg/dL), elevated testosterone (590.2 ng/dL, N <75 ng/dL) and elevated 11-deoxycortisol (4650 ng/dL N-<32 ng/dL). 24 hour urinary free cortisol was 2810mcg/mL (<45mcg/dL). MRI of pituitary was normal. CT scan of abdomen/pelvis showed normal bilateral adrenal glands and innumerable enhancing masses throughout the abdomen with the largest mass near the distal ileum and cecum. Biopsy of right lower abdominal mass revealed adrenocortical morphology with immunohistochemical staining positive for inhibin, synaptophysin and calretinin. Ki-67 index was 10-15%, suggestive of low-grade adrenocortical carcinoma. A CT scan done one and half years prior noted a 4.4 cm soft tissue mass in the right lower mesentery supporting origin of the tumor from the mesentery. Hypercortisolism was controlled with Metyrapone 250 mg BID. Mitotane 1000 mg bid was initiated but patient developed peritoneal carcinomatosis within 1 month. Conclusions: Our case is remarkable for the development of a metastatic ACC from an ectopic adrenal tissue with normal bilateral adrenal glands. Ectopic ACC is very rare with only a handful of cases reported in the literature. This is the first reported case of ACC arising from the mesentery. Ectopic adrenal tissue can be found close to the adrenal glands, along the path from gonads to adrenal glands or in association with the gonads. In the setting of ACTH independent Cushing’s syndrome with normal adrenal glands, physicians should direct their search to a functioning ectopic adrenocortical tissue. Concomitant DHEAS secretion suggests ectopic ACC. If surgery is not an option due to metastatic disease, a multidisciplinary approach should be adopted to control tumor growth and associated symptoms. In such cases, control of the hypercortisolemia can be achieved with adrenolytic medications such as Metyrapone, Ketoconazole or Mitotane. Adjuvant chemotherapy (Mitotane and combination of cytotoxic drugs) might be considered for metastatic ACC treatment.