1409 Casting a Wide Net to Find a Rare NET: A Case of Gallbladder Large Cell Neuroendocrine Carcinoma

Abstract

INTRODUCTION: Primary neuroendocrine tumors (NETs) of the gallbladder account for <0.5% of all NETs. 1 Large-cell neuroendocrine carcinoma (LCNEC) represents an extremely rare subtype of this uncommon malignancy, and as such, clinical features, optimal treatment, and overall prognosis remains largely unknown. CASE DESCRIPTION/METHODS: A 58-year-old women presented to the emergency department with food intolerance due to nausea and pain at her cholecystostomy drain site. Two weeks prior, she had been admitted to an outside hospital for severe right upper quadrant (RUQ) pain without nausea, vomiting, or fever. Work-up included computed tomography (CT) of the abdomen and a RUQ ultrasound, which appeared to reveal changes of cholecystitis and cholelithiasis. Cholecystectomy was attempted, but due to an intraoperative finding of a hardened gallbladder mass, the procedure was aborted, and a surgical cholecystostomy tube was placed instead. Upon admission to our hospital, the patient had normal vital signs. Physical examination was notable for mild RUQ tenderness and a cholecystostomy drain with small amounts of dark bilious fluid. Laboratory testing was significant for total bilirubin of 3.6 mg/dL, alkaline phosphatase of 557 U/L, and AST of 57 U/L. Repeat CT of the abdomen revealed a mass in the hepatic lobe and circumferential soft tissue spanning the tract of the cholecystostomy tube. Endoscopic retrograde cholangiopancreatography (ERCP) showed an extrinsically narrowed proximal duodenum and a 1.5 cm intracholedochal tumor thrombus. Histopathology revealed high grade LCNEC with 80% Ki67 proliferative activity. Oncology was consulted, and although chemotherapy was initiated during the hospitalization, the patient expired from cardiac arrest days after discharge. DISCUSSION: Patients with LCNEC present with non-specific symptoms such as abdominal pain or weight loss, and imaging cannot reliably differentiate gallbladder NETs from adenocarcinoma or other pathology. Thus, many are identified incidentally peri-cholecystectomy. Treatment options include resection if distant metastases are not present; if unresectable, palliative chemotherapy and radiation may be administered. The overall prognosis of gallbladder NETs is poor, even worse than gallbladder adenocarcinoma. Early detection with aggressive surgical resection is believed to be the only potential for cure.