Ampullary Neuroendocrine Tumor: A Rare Cause of Recurrent Abdominal Pain

Abstract

Introduction: Ampullary neuroendocrine tumor (ANET) is a rare GI malignancy, representing less than 1% of GI neuroendocrine tumors and less than 2% of ampullary tumors. One hundred thirty-nine ANET cases have been reported in the SEER database. Case Report: Our patient is a 21-year-old Vietnamese man who complained of 6 years of non-specific, intermittent upper abdominal pain. Physical examination revealed mild epigastric and right upper quadrant tenderness. Laboratory evaluation was normal, including liver function tests and pancreatic enzymes. An EGD revealed a nodular ampullary mass with normal overlying mucosa. Mucosal biopsies were normal. EUS revealed a 1.5-cm hypoechoic heterogeneous ampullary mass, and FNA revealed cells containing uniform, rounded nuclei with speckled chromatin consistent with a welldiff erentiated neuroendocrine tumor. Radiographic imaging for metastatic disease was unremarkable, and serum chromogranin A, gastrin, and 24-hour urine HIAA levels were normal. Conventional treatment often is a pancreaticoduodenectomy; however, in this case a transduodenal ampullectomy was performed. Pathology confirmed a well-differentiated neuroendocrine tumor (WHO grade 1) with clear 2-mm margins, without lymphovascular or perinueral invasion. Further characterization psammoma calcifications, positive immunoreactivity for somatostatin, CD8/18, chromogranin A, synaptophysin, and focal positivity of s100 and Ki67 (<1%). Of note, the sample was negative for c-KIT, gastrin, CD34 and CD68. The patient's recovery was uneventful and he is symptom and disease free at 18 months. Discussion: ANET are rare tumors and only one-quarter of such patients present with abdominal discomfort. Because ANET are rare, biological behavior and prognosis is controversial. Traditional treatment is often a pancreaticoduodenectomy; however, local and endoscopic resections have been successful. Conclusion: ANET are a rare cause of recurrent abdominal pain, and local exision of small ANETs can be an alternative, less morbid treatment for young patients.Figure