SUN-928 Adrenal Plasmacytoma in Multiple Myeloma Patient-An Unusual Presentation

Introduction: Extramedullary plasmacytomas are plasma cell tumors that arise outside of the bone marrow. They are solitary lesions, and are most often located in the head and neck region, mainly in the upper aerodigestive tract. However, involvement of adrenal gland is extremely rare, with only nine case reports published to date. A mass in the adrenal gland carries a broad differential, and identification is important, as diagnosis drives treatment options. CT imaging with attenuation, timing of contrast medium washout, size, and shape, with biopsy is necessary for diagnosis of a high Hounsfield unit mass. Ruling out pheochromocytoma before biopsy of the adrenal glands is crucial. Clinical Case: A 64-year-old female was diagnosed with multiple myeloma after presenting with back pain and altered mental status. Imaging revealed diffuse lytic lesions in clavicles, pelvis, calvarium, long bones, ribs, and compression fractures of T8, T10, and T12 vertebral bodies. A 1.5 cm left adrenal nodule was also noted. She was treated with bortezemib, cyclophosphamide, lenalidomide, and dexamethasone, and clinically improved. Four months after initial presentation, patient was to undergo chemotherapy with melphalan and autologous stem cell transplantation. Further imaging was performed, and CT Chest revealed an enlarging left adrenal mass measuring 3.0 x 3.2 cm with increased attenuation at 37 Hounsfield units and lobulated borders with no invasion of adjacent structures. The endocrinology team was consulted for evaluation of the adrenal mass, as patient’s disease from multiple myeloma was presumed to be in remission. Differential for the adrenal mass included pheochromocytoma, primary adrenal carcinoma, and metastatic disease from multiple myeloma vs other primary. Plasma fractionated metanephrines and DHEAS were within normal range. CT guided core biopsy was performed. Cytology revealed diffuse infiltrate of atypical plasma cells. IHC studies were positive for CD138, CD56, and showed lambda light chain restriction. Cyclin D1 stain was negative, consistent with plasmacytoma. Clinically, the patient started developing progressive disease, including cutaneous plasmacytomas, and she was treated with additional chemotherapy. Conclusion: Adrenal plasmacytoma is extremely rare, and in a patient with multiple myeloma, should be considered in the differential diagnosis of a rapidly enlarging adrenal mass with high CT attenuation. CT guided biopsy is the definitive test for diagnosis. References: Li Y., Guo Y.-K., Yang Z.-G., Ma E.-S., Min P.-Q. Extramedullary plasmacytoma involving the bilateral adrenal glands on MR imaging. Korean Journal of Radiology. 2007;8(3):246–248. doi: 10.3348/kjr.2007.8.3.246.