1370 An Extremely Rare Presentation: Primary Neuroendocrine Tumor

Abstract

INTRODUCTION: This is the case of a 63-year old asymptomatic male with history hypertension who was found with an abnormal gallbladder in a routine abdominal sonogram for kidney cysts. The gallbladder walls appeared thickened with low and intermediate level intraluminal echoes interpreted as tumefactive sludge. Given asymptomatic presentation, no further workup was solicited. CASE DESCRIPTION/METHODS: A follow up abdominal MRI displayed further gallbladder asymmetry with focal thickening of the right lateral aspect of the proximal fundus. A PET CT failed to show significant FDG concentration at the soft tissue density on the fundus. Upon evaluation, the patient denied abdominal pain, jaundice or weight loss, among others. All laboratories were within normal limits including CEA and CA 19-9. The patient was referred to surgery service who initially stated no surgical management due to asymptomatic presentation and negative PET CT. However, cholecystectomy was performed by a hepatobiliary surgeon upon further increase in size of the gallbladder lesion. Surgical pathology sample showed sheets of small atypical cells, focally growing in a cord like and nested pattern. Immunology stains were done which showed a poorly differentiated component with positive markers for chromogranin and synaptophysin. These findings were suggestive of a poorly differentiated neuroendocrine carcinoma. Serum chromagranin A and 5- HIAA in urine collection were requested after resection and were normal. DISCUSSION: Primary neuroendocrine tumors of the gallbladder are exceedingly rare, comprising 0.2% of all neuroendocrine tumors. Most neuroendocrine tumors of the gallbladder are diagnosed as an incidental finding on cholecystectomy since most patients present with non-specific symptoms including upper abdominal pain, discomfort, jaundice and weight loss. Carcinoid syndrome is seldom present as it is associated with less than 1% of neuroendocrine tumors of the gallbladder. The rarity of this tumor, along with its asymptomatic presentation and poor prognosis, supports the claim that further research is needed to achieve early detection and better outcomes. This case also serves to illustrate that an asymptomatic presentation, negative PET CT, and increasing gallbladder thickening on repeated imaging should not be overlooked.