# A rare incidental finding during routine pathological evaluation of gallbladder specimen: a case report

## TL;DR

A rare gallbladder neuroendocrine tumor was discovered during routine pathology after surgery, highlighting the importance of histopathology in early detection.

## Contribution

This case report emphasizes the role of histopathology in identifying rare gallbladder neuroendocrine tumors during routine evaluation.

## Key findings

- A grade 1 neuroendocrine tumor was found at the cystic duct margin during routine histopathology.
- The patient remained disease-free for 5 years after surgical resection without adjuvant therapy.
- Histopathology and immunohistochemistry were critical in distinguishing the tumor from common gallbladder conditions.

## Abstract

Neuroendocrine tumors (NETs) of the gallbladder are rare, often discovered incidentally, with unclear pathogenesis and management strategies.

A 51-year-old man with hypertension presented with abdominal pain and a positive Murphy’s sign. After laparoscopic cholecystectomy for suspected acute cholecystitis, histopathology revealed a grade 1 NET at the cystic duct margin, invading the subserosa (pT2). Staging showed no metastases, though pericholedochal lymph nodes were enlarged. A second surgery resected the cystic duct and regional lymph nodes, revealing no residual tumor. No adjuvant therapy was given, and the patient remains disease-free at 5 years.

Gallbladder NETs often mimic common biliary conditions, making the preoperative diagnosis challenging due to nonspecific findings. This case highlights the pathology’s key role in the diagnosis of asymptomatic early-stage tumors and suggests a favorable prognosis for well-differentiated NETs with surgical management, despite unclear adjuvant therapy guidelines.

NETs of the gallbladder are uncommon with nonspecific clinical and imaging features. This rare case emphasizes the importance of routine pathological examination of gallbladder specimens in detecting and grading of asymptomatic and early stage tumors such as NETs.

•Rare NET of gallbladder found at cystic duct margin (<0.5% of NETs) during routine histopathology post-cholecystectomy.•Histopathology and immunohistochemistry key to distinguish NETs from common gallbladder issues despite nonspecific findings.•Positive margin led to resection of cystic duct and nodes; disease-free at 2 years without adjuvant therapy for low-grade NET.

Rare NET of gallbladder found at cystic duct margin (<0.5% of NETs) during routine histopathology post-cholecystectomy.

Histopathology and immunohistochemistry key to distinguish NETs from common gallbladder issues despite nonspecific findings.

Positive margin led to resection of cystic duct and nodes; disease-free at 2 years without adjuvant therapy for low-grade NET.