Benign Morphologic Mimics and Diagnostic Pitfalls in Gallbladder Adenocarcinoma

Abstract Gallbladder adenocarcinoma is an aggressive malignancy that often presents with nonspecific clinical and radiologic features, leading to significant diagnostic challenges. Several benign and reactive conditions can closely mimic carcinoma, resulting in both overdiagnosis and underdiagnosis. We present a case series of five cholecystectomy specimens demonstrating a spectrum of lesions that simulated gallbladder adenocarcinoma, including xanthogranulomatous cholecystitis, adenomyomatosis with florid Rokitansky–Aschoff sinuses, reactive epithelial atypia, benign hyperplastic polyp, and metastatic colorectal adenocarcinoma. These entities showed overlapping gross and microscopic features such as wall thickening, glandular proliferation, and cytologic atypia. Careful evaluation of architectural patterns, stromal response, and mucosal continuity, along with judicious use of immunohistochemistry, enabled accurate diagnosis. This series highlights key morphologic pitfalls and emphasises a systematic approach to avoid diagnostic errors in routine surgical pathology practice.