Neuroendocrine tumors of the gallbladder: a case report and review of the literature.

Introduction: Primary gallbladder neuroendocrine tumors are extremely rare, representing 0.2% of all neuroendocrine tumors. The diagnosis is incidental in most cases.

Case Presentation: We describe the case of a 57-year-old Caucasian man who underwent laparoscopic cholecystectomy for the evaluation of a gallbladder polyp that had been incidentally detected by ultasonography. Histologically, his lesion was composed of monomorphic cells that contained small round nuclei and that were organized in small nodular, trabecular, and acinar structures. His cells were positive for chromogranin A and synaptophysin, and a diagnosis of "typical" carcinoid of the gallbladder was made. His post-operative computerized axial tomography, 111In-pentetreotide scintigraphy, and hormone-specific marker results were negative. He is disease-free 45 months after surgical treatment.

Conclusions: Characteristic pathological findings of the gallbladder neuroendocrine tumors predict the prognosis. Whereas classical carcinoids of the gallbladder only rarely have a metastatic or invasive phenotype, the "atypical" variants are more aggressive and are associated with a poorer prognosis. Given the difficulty in distinguishing between benign and malignant lesions in the pre-surgical setting, we tend to consider each polypoid-like lesion of the gallbladder to be a high-risk lesion if it is larger than 1 cm and, as a result, to emphasize the need for cholecystectomy in all cases, relying on the pathological and immunohistochemistry analyses for the final diagnosis.