A Case of Mixed Neuroendocrine Non-Neuroendocrine Tumor Diagnosed after Laparoscopic Cholecystectomy and Lymph Node Resection

An 81-year-old woman presented to our hospital with a chief complaint of hematuria. She was referred to our department of surgery because a 20-mm nodular lesion in the hilar region was noted on abdominal CT. Abdominal US revealed a 6-mm elevated lesion in the gallbladder, a gallbladder stone, and an enlarged lymph node with a diameter of 24 mm adjacent to the neck of the gallbladder. Contrast-enhanced MRI showed ring-enhanced lesions in the same nodule, and diffusion-weighted images gave a faint high signal, suggesting an enlarged lymph node. Laparoscopic cholecystectomy and lymph node (#12c) resection were performed for diagnostic and therapeutic purposes. Histopathological examination enabled the elevated lesion of the gallbladder to be diagnosed as a mixed neuroendocrine non-neuroendocrine neoplasm (MiNEN). The enlarged lymph node was found to be a metastasis of the tumor. Hepatoduodenal mesenteric lymph node dissection was performed on postoperative day 36 as an additional resection, but no metastasis was found in the 12 resected lymph nodes. The final stage was pT2N1M0 pStage IIIb. We report a case of MiNEN with a generally poor prognosis, in which diagnostic surgery and additional regional lymph node dissection were performed.