1402 Metastatic Merkel Cell Carcinoma With Isolated Pancreatic Metastases

Abstract

INTRODUCTION: Merkel cell carcinoma (MCC) is a rare neuroendocrine skin malignancy. It has a high risk of nodal metastases (25%) but distant metastases are uncommon (8%). Liver and lung are the most common metastatic sites reported. Pancreatic metastases are uncommon and are associated with other sites of metastases. We report a rare case of Merkel cell carcinoma with isolated pancreatic metastases. CASE DESCRIPTION/METHODS: A 53-year-old Caucasian man presented with a 9-month history of an enlarging crusting lesion on the anterior chest wall. Physical examination showed a 15 × 20 cm crusty erythematous skin lesion in the upper mid chest. He also had palpable right axillary and left pre-clavicular lymphadenopathy. He underwent wide local excision with bilateral axillary and left neck lymph node dissection. Surgical pathology revealed node positive stage III MCC with a focus of squamous cell carcinoma. All margins were negative. He was started on adjuvant Radiation Therapy (RT) after discussion in the multidisciplinary tumor board but presented after 1-fraction with new upper abdominal discomfort. A CT scan showed areas of hypoattenuation in the pancreas with enlarged peri-pancreatic lymph nodes (Figure 1). EUS showed similar findings (Figure 2). EUS guided FNA was consistent with MCC. He underwent six cycles of chemotherapy with cisplatin/etoposide with complete resolution of the pancreatic masses and lymphadenopathy (Figure 3). However, 1 month later he passed away due to sudden cardiac arrest. DISCUSSION: Merkel cell carcinoma (MCC) is a neuroendocrine neoplasm of the skin, arising from Merkel cells at dermo-epidermal junction. It is a rare cancer with incidence of 0.7 per 100,000 persons. It predominately effects elderly, light-skinned and immunocompromised people. Merkel cell polyomavirus may play a role in the pathogenesis. Common sites of distal involvement include liver, lungs and bone. Pancreatic metastasis is rare with only a few cases reported, most of which were associated with other sites of metastases. EUS is a less-invasive means of confirming diagnosis and ruling out pancreatic adenocarcinoma. There is no standard modality of management for MCC with pancreatic metastasis. Chemotherapy, radiation therapy, surgical removal and immunotherapy with PD-L1 inhibitors are options for management. Overall prognosis is poor, with median survival around 7.5 months. Our patient responded very well to therapy but passed away from cardiac arrest 9 months after initial diagnosis.