Large cell neuroendocrine carcinoma of the gallbladder

We report two cases of primary large cell neuroendocrine carcinoma (LCNEC) of the gallbladder, which, to the best of our knowledge, represent the firs t description of this entity. One of the tumors consisted entirely of LCNEC , whereas the second tumor was composed of LCNEC and the more common intest inal-type adenocarcinoma. Both tumors were morphologically similar to their pulmonary counterpart and were characterized by large cells with prominent nucleoli, coarse chromatin, and a high mitotic rate. The cells showed an o rganoid growth pattern with rosette formation and frequent areas of necrosi s. Panendocrine markers were expressed in a variable proportion of tumor ce lls in both cases, and one of the cases also showed focal positivity for ty pe 2 somatostatin receptors. One of the tumors followed a rapidly fatal cou rse despite aggressive surgical treatment and chemotherapy administration, and the second patient is still alive and disease-free 12 months after surg ery. The description of these two cases of LCNEC of the gallbladder is sign ificant for two reasons. From an academic standpoint, we now know that all the neuroendocrine tumors described in other organs can arise de novo in th e gallbladder. More importantly, however, the recognition of this rare tumo r type carries important clinical implications in regard to the use of chem otherapeutic agents and supplemental treatments (for example, somatostatin analogs).