A Unique Case of Corticomedullary Mixed Tumor Composed of Both Adrenal Cortical Cells and Pheochromocytes

Introduction or Background: Corticomedullary mixed tumors of the adrenal gland was first described in 1969 by Mathison and Waterhouse. It is defined as a single tumor mass of the adrenal gland that histopathologically has presence of adrenal cortical and medullary cells. Such mixed tumors involving the cortical and medullary components of the adrenal glands are very rare. Clinical Case (including diagnostic evaluation, treatment, and follow-up):A 67 year old woman with a history of hypertension and osteoporosis presents for incidental adrenal adenoma. Hypertension was controlled well with olmesartan 40mg, hctz 25mg, and amlodipine 2.5mg. Abdominal CT scan showed a 2.6 cm enhancing left adrenal nodule with delayed wash- out phase. Biochemical testing showed elevated plasma free metanephrine (132pq/ml, n < or = 57pq/ml) and abnormal 1mg dexamethasone suppression test (10.4mcg/dL, n <2mcg/dL). ACTH was suppressed. Patient underwent left adrenalectomy, after pretreatment with doxazosin. Surgical pathology report showed an unusual neoplasm consisting of a single nodule composed of intermixed aggregates of cortical cells and pheochromocytes displaying morphologic features of adrenal adenoma and pheochromocytoma. Also intermixed with the adenoma was a 3mm myelolipoma. Post surgery, the patient was treated with hydrocortisone for symptoms of adrenal insufficiency. Post surgery, she was able to stop amlodipine and hctz and is on 10 mg olmesartan on alternate days.. She remains on a weaning dose of hydrocortisone at the time of abstract submission. Clinical Lesson(s) or Conclusion(s) (emphasizing the learning point[s] and implications for clinical practice)This unique case report highlights the importance of appropriate workup for incidental adrenal adenoma and keeping in mind the rare possibility of mixed endocrine tumours. A single mixed tumor of the adrenal gland is rare but exhibits distinct morphologic features of both a cortisol producing tumor along with a pheochromocytoma. Furthermore, a concurrent intermixing of a myelolipoma within an adrenal corticomedullary mixed tumor is rarely reported.