SUN-379 Transformation of Adrenal Adenoma into Adrenocortical Carcinoma in a Cushing Syndrome Patient after Surgery

Background: Adrenocortical carcinoma (ACC) is a rare and aggressive malignancy with annual incidence of 0.5-2.0 cases/million. More unusual is transformation of benign adrenal adenoma to ACC after complete resection. Clinical case: A 72 year old woman with prior history of presumed nonfunctional left (L) adrenal adenoma presented with Cushing’s Syndrome (CS) in 2016. Imaging showed increase in size of her L adrenal adenoma from 1.5 cm in 2007 to 3.7 cm in 2016. On CT, it had a 1.6 X1.3 cm internal hypodense component, -15 Hounsfield units (HU), and surrounding solid component 78 HU on portal venous phase with 42% relative washout. Biochemical testing suggested ACTH-independent CS: elevated cortisol 33.79 ug/dL (4.30-22.40ug/dL), abnormal 1 mg dexamethasone suppression test (DST) cortisol 33.59 ug/dL (4.30-22.40ug/dL), ACTH undetectable <5 pg/mL (7.2-63 pg/mL), low-dose 48hr DST cortisol 37.21 ug/dL (4.30-22.40 ug/dL), normal metanephrine < 0.20 nmol/L (<0.50 nmol/L), normal normetanephrine 0.41 nmol/L (<0.90 nmol/L), aldosterone < 4.0 ng/dL (n < 21 ng/dL). She underwent uncomplicated robotic resection of the adenoma. Surgical pathology was consistent with benign adenoma, Weiss Score = 2 - mitotic rate 12/50 HPF; more than 33% diffuse architecture. She recovered well and weaned off hydrocortisone. In February 2018 she developed recurrent symptoms of CS. Repeat tests showed midnight salivary cortisol 1250 ng/dL (n <100 ng/dL), AM cortisol 39.7 ug/dL (4.30-22.40ug/dL), DHEA-S 205 (<15 - 157 mcg/dL), ACTH <5 pg/mL (7.2-63 pg/mL). Repeat MRI showed large lobulated heterogeneous L adrenal mass increased in size compared to prior despite interval resection- overall size 6.8 x 4.1 x 5.9 cm, with new scattered enhancing nodules superior & posterior to L kidney. She was again referred for surgical resection with high suspicion of conversion to ACC. She had repeat robotic resection with conversion to open L adrenalectomy and L nephrectomy, splenectomy, partial pancreatectomy, and resection of a small piece of the diaphragm. Repeat surgical pathology showed metastatic ACC with metastases to the diaphragm, omentum, perinephric and perisplenic adipose tissue, and positive margins. Post-operatively she has been treated with mitotane, cisplatin, etoposide, and doxorubicin. She is currently on mitotane therapy alone due to cardiotoxicity from her chemotherapy. Conclusion: This is an uncommon case of transformation of benign adrenal adenoma to metastatic ACC. This highlights the uncertainties regarding postoperative follow-up of adrenal adenomas and the potential need for continued surveillance post-resection. Reference: Fareau GG, et al. Diagnostic challenges in adrenocortical carcinoma: recommendations for surveillance after surgical resection of selected adrenal nodules. Endocr Pract. 2007, Oct; 13(6):636-41