Imprint cytological feature of large cell neuroendocrine carcinoma of the gallbladder: a case report.

Large cell neuroendocrine carcinoma (LCNEC) is a rare poorly differentiated carcinoma with neuroendocrine differentiation showing aggressive clinical behavior. We herein report a case of gallbladder LCNEC, which was difficult to differentiate from poorly differentiated adenocarcinoma. An imprint cytology was very useful for the final diagnosis in this case. A 56-year-old male with left exophthalmos was admitted to the hospital. Radiological examinations revealed the presence of a left gallbladder tumor with orbital metastasis. The histological diagnosis was poorly differentiated adenocarcinoma, and intensive chemoradiotherapy was administered. Unfortunately, the patient died of extensive metastases 36 months after the initial onset of symptoms. An autopsy revealed a tumor mass in the gallbladder associated with multiple liver and peritoneal metastases. Imprint cytology of the main tumor revealed cytological features of LCNEC, and additional histological examinations confirmed this diagnosis. Although performing a histological examination is important for making a final diagnosis, imprint cytology is powerful tool for differential diagnosis of LCNEC, especially in patients with carcinoma with poor differentiation.