P0178 - Not Another Acute Cholecystitis - A Rare Case of Mixed Adenoneuroendocrine Carcinoma of the Gallbladder

Anaisa Quintanilla-Arteaga, MS¹, Promise Lee, MD², Xianzhong Ding, MD^3
1Loyola University Chicago Stritch School of Medicine, Chicago, IL; ²Loma Linda University Medical Center, Loma Linda, CA; ³Loyola University Medical Center, Chicago, IL

Introduction: Gallbladder cancers are rare and account for < 1% of all cancers. Cholelithiasis is the greatest risk factor. With a handful of case reports in literature, we present a rare case of mixed adenoneuroendocrine carcinoma of the gallbladder with liver metastasis following a typical acute cholecystitis presentation.

Case Description/Methods: A 72 year old female with a history of hyperlipidemia presented with acute right upper quadrant abdominal pain, mild leukocytosis, and ultrasound findings concerning for acute cholecystitis requiring cholecystectomy. Acute and chronic inflammatory changes with focal necrosis associated with a chronically impacted stone with abnormal appearing tissue on the lateral edge of the gallbladder and anterior surface of the liver concerning for possible malignancy were noted in the operation. Histopathological findings correlated with a mixed adenoneuroendocrine carcinoma (MANEC) diffusely involving the gallbladder wall and extending to the liver parenchymal margin with direct invasion with no discrete mass identified. The patient underwent partial liver resection and multidrug chemotherapy regimen with disease progression.

Discussion: MANEC is a rare and aggressive neoplasm characterized by the presence of both adenocarcinoma and neuroendocrine components, confirmed through histopathology and immunohistochemistry. MANEC typically present as a discrete mass, and are identified as localized growths within the affected organ, often forming polypoid or nodular masses. The pathogenesis of MANECs remains unclear, but it is thought that these tumors arise from a common pluripotent stem cell or through a process of divergent differentiation. Biological behavior and prognosis of the neoplasm is directed in large part by the neuroendocrine component. Limited studies suggest that in most MANEC cases, only one histologic component metastasizes. Treatment typically involves surgical resection, possibly followed by adjuvant chemotherapy or radiotherapy.The occurrence of MANEC neoplasms as discrete masses is exceedingly rare. Here we report a case of MANEC presenting as acute cholecystitis with diffuse involvement of the gallbladder wall and liver metastasis without a formed mass. The atypical presentation and rapid progression of disease underscore the need for heightened awareness and comprehensive histopathological evaluation to ensure accurate diagnosis and appropriate treatment.


Disclosures:


Anaisa Quintanilla-Arteaga, MS¹, Promise Lee, MD², Xianzhong Ding, MD³. P0178 - Not Another Acute Cholecystitis - A Rare Case of Mixed Adenoneuroendocrine Carcinoma of the Gallbladder, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.