2031 Metastatic Neuroendocrine Tumor of Unknown Primary Presenting as Acute Gastrointestinal Bleed With Hemorrhagic Shock

Abstract

INTRODUCTION: Neuroendocrine tumors (NETs) are often localized, however up to 50% of cases can be metastatic, with 13% having an unknown primary . Most NETs are identified during work up of related symptoms or functional syndrome (i.e. carcinoid) or found incidentally. We present a case of metastatic NET of unknown primary origin presenting as acute hemorrhagic shock from gastrointestinal bleeding. CASE DESCRIPTION/METHODS: A 21-year-old male presented with hematochezia, abdominal pain and nausea and was admitted to the ICU for hemorrhagic shock with a drop in hemoglobin from 14.5 to 8.2. EGD showed 15 mm, necrotic, oozing duodenal ulcer without visible blood vessel, treated with Hemospray. Recurrent episode of bleeding necessitated IR-guided GDA embolization. CT imaging initially identified, and later MRI confirmed three complex hepatic lesions in both right and left lobes of the liver . IR-guided liver biopsy showed low-grade, well-differentiated metastatic NET, Ki-67 1%. Gastrin and chromogranin A levels were elevated at 166 pg/mL and 223 ng/mL respectively. Otreotide scan found enhancement in the liver consistent with metastatic NET, without identification of a primary site. He was started on octreotide infusions. Additional work-with CT chest and pelvis, repeat EGD/EUS and colonoscopy were negative for primary tumor. He underwent laparotomy with left lateral segment partial hepatectomy, microwave ablation of the remaining liver lesion and cholecystectomy. DISCUSSION: NETs are typically indolent cancers involving the small intestine, appendix, colon/rectum, pancreas or lung. Common sites of metastasis include the liver, peritoneum, lymph nodes and lungs. The majority of metastatic NETs have an identifiable primary site, but it is important to recognize that many can have an unknown origin. Understanding the primary site of NETs is an important prognostic factor in overall survival. In general, metastatic disease is associated with a poorer prognosis, particularly in the setting of unknown primary origin. This case illustrates that patients with NETs can have a variable initial presentation, including acute GI bleeding from peptic ulcer disease. In addition, this case shows that despite appropriate diagnostic testing including biochemical markers, anatomic and functional imaging studies, endoscopic procedures and tissue biopsies, the primary site of metastatic NETs can go unidentified, which can effect definitive treatment options.