SUN-181 A Case of Metastatic Merkel Cell Carcinoma Within a Cortisol-Producing Adrenal Adenoma

Introduction: Metastasis within another tumor is rare, and exceedingly more rare within a functional adrenal adenoma. Merkel cell carcinoma (MCC) is an aggressive and rare neuroendocrine carcinoma of the skin. We present a patient with history of MCC who presented with an adrenal mass, found to be metastatic MCC within a cortisol-producing adrenal adenoma. Case description: 54 year old male with a history of type 2 diabetes, hypertension, MCC of right thigh, presented for adrenal mass. He was initially evaluated in the ER for severe abdominal pain for 4 days. He had a CT abdomen done, which showed 6cm right adrenal mass with extensive fat and soft tissue component within it. Hounsfield units within solid area measured up to 47 units, and surrounding area measured -3 Hounsfield units. His history was significant for MCC of right thigh, type 2 diabetes, HTN, obesity and OSA. Pathology from MCC resection showed no evidence of invasion and clear margins, but he did have microscopic focus on inguinal lymph node biopsy. His PET scan was negative except for low uptake in a 6cm right adrenal lesion that was considered benign-appearing. He completed radiation therapy to right thigh and groin. Physical exam was notably negative for any cushingoid features. Aldosterone, renin and plasma metanephrines were normal. Cortisol after dexamethasone suppression test was elevated, and ACTH and DHEAS were low, raising suspicion of Cushing’s syndrome. He had right adrenalectomy and was then started on steroid replacement. Pathology showed adrenocortical adenoma with a 2cm well-circumscribed mass within the adenoma positive for metastatic MCC with lymphovascular invasion. ACTH stimulation testing was performed at follow up after holding hydrocortisone for over 24 hours, and was consistent with suppression of glucocorticoid axis in the contralateral adrenal gland. Discussion: MCC and metastasis within a functional adrenal tumor are both rare occurrences. Our patient had positive regional lymph node involvement at the time of diagnosis, and although the initial PET scan was interpreted as showing an benign adrenal adenoma, it is likely that this represented distant metastasis. Labs indicated that the surrounding adenoma was likely cortisol-producing. To our knowledge, this is the first case reported of metastatic MCC within a functional adrenal adenoma. References: Baek, SH, et al. “Merkel cell carcinoma of the Axilla and Adrenal Gland: A Case Report with Imaging and Pathologic Findings.” Case Reports in Medicine. Volume 2015, Article ID 931238. Dongyan, L., S. Kumar. “An exceedingly rare adrenal collision tumor: adrenal adenoma-metastatic breast cancer-myelolipoma.” Journal of Community Hospital Internal Medicine Perspectives, 2017. Vol. 7, No. 4, 241-244. Martin, JT, et al. “Metastatic adenocarcinoma within a functioning adrenal adenoma: a case report.” Cases Journal 2009, 2:7965.