ABSTRACT
Gallbladder neuroendocrine tumors (GB-NETs) comprise only 0.5% of all NET cases, and their biology has been incompletely characterized. In the present study we report the case of a 50-year-old male patient with GB-NET who was admitted to Naito Hospital with diarrhea as the main complaint. At initial diagnosis, serum carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) levels were within the normal range. Abdominal ultrasonography and contrast-enhanced computed tomography (CT) revealed gallbladder adenomyomatosis and cholecystitis, and an 8-mm pedunculated polypoid lesion was found in the neck of the gallbladder using drip infusion cholecystocholangiography-CT. As it was considered a benign polyp, laparoscopic cholecystectomy was performed. Pathological examination revealed a polypoid lesion that comprised NET cells with a cord-like or ribbon-like arrangement, and the cells exhibited positive immunostaining for chromogranin A and synaptophysin. In addition, immunohistochemical staining showed a Ki-67 index (i.e., proliferation index) of <1%, and no necrosis or mitotic figures were observed in the background. Based on these observations, we diagnosed the following: GB-NET, G1, 10x12 mm in size and located in the gallbladder neck. According to the World Health Organization 2010 classification, NET G1 is a well-differentiated tumor, with the tumor cells having a low proliferative potential [Ki-67 index ≤2%; mitotic figure number <2 (/10 HPF)]. It is regarded as a low- to mild-grade malignancy. Low-grade GB-NET occurs relatively rarely, and no clear guidelines have been formulated regarding its surgical treatment, such as minimal surgical excision margins or lymph node dissection. Detailed treatment recommendations should be developed after systematic studies of additional cases of GB-NET.
ABSTRACT
The patient was a 67-year-old man under follow-up after gastric cancer surgery. An abdominal CT scan performed 1 year earlier had shown an approximately 14-mm hypovascular mass in the pancreatic body; however, he did not consent to treatment and was followed up for 1 year. A blood workup showed that the fasting blood glucose level, which had been within normal limits, was elevated to 174 mg/dl (normal, 70-109 mg/dl), and the HbA1c level was 12.0% (normal, 4.3-5.8%). Abdominal CT revealed an approximately 20-mm mass in the pancreatic body and an approximately 12-mm mass in the pancreatic tail, and magnetic resonance imaging cholangiopancreatography (MRCP) showed discontinuity of the main pancreatic duct (MPD). Since these findings led to the suspicion of invasive ductal carcinoma (IDC) of the pancreas developing in the pancreatic body and tail, we performed distal pancreatectomy with splenectomy. Histologically, IDCs were observed in the pancreatic body and tail. However, PanIN was not observed in the MPD between the two carcinomas. They were diagnosed as independent invasive ductal carcinomas of the pancreas.
