Neuroendocrine carcinoma of the minor papilla with pancreas divisum: a case report and review of the literature

Abstract

Background: Neuroendocrine tumors of the minor papilla are very rare, and only 20 cases have been reported in the literature. Neuroendocrine carcinoma of the minor papilla with pancreas divisum has not been reported previously, making this the first reported case. Neuroendocrine tumors of the minor papilla have been reported in association with pancreas divisum in about 50% of cases reported in the literature. We herein present our case of neuroendocrine carcinoma of the minor papilla with pancreas divisum in a 75-year-old male with a systematic literature review of the previous 20 reports of neuroendocrine tumors of the minor papilla.

Case presentation: A 75-year-old Asian man was referred to our hospital for evaluation of dilation of the main pancreatic duct noted on abdominal ultrasonography. Magnetic resonance cholangiopancreatography and endoscopic retrograde cholangiopancreatography showed a dilated dorsal pancreatic duct, which was not connected to the ventral pancreatic duct; however, it opened to the minor papilla, indicating pancreas divisum. The common bile duct had no communication with the pancreatic main duct and opened to the ampulla of Vater. A contrast-enhanced computed tomography scan showed a 12-mm hypervascular mass near the ampulla of Vater. Endoscopic ultrasonography showed a defined hypoechoic mass in the minor papilla with no invasion. The biopsies performed at the previous hospital found adenocarcinoma. The patient underwent a subtotal stomach-preserving pancreaticoduodenectomy. The pathological diagnosis was neuroendocrine carcinoma. At the 15-year follow-up visit, the patient was doing well with no evidence of tumor recurrence.

Conclusion: In our case, because the tumor was discovered during a medical check-up relatively early in the course of disease, the patient was doing well at the 15-year follow-up visit, with no evidence of tumor recurrence. Diagnosing a tumor of the minor papilla is very difficult because of the relatively small size and submucosal location. Carcinoids and endocrine cell micronests in the minor papilla occur more frequently than generally thought. It is very important to include neuroendocrine tumors of the minor papilla in the differential diagnosis of patients with recurrent pancreatitis or pancreatitis of unknown cause, especially for patients with pancreas divisum.

Keywords: Minor papilla; Neuroendocrine carcinoma; Neuroendocrine tumor; Pancreas divisum; Pancreatitis.

Fig. 1

a Magnetic resonance cholangiopancreatography showing a dilated dorsal pancreatic duct that was not connected with the ventral pancreatic duct and opened to the minor papilla. The common bile duct had no communication with the pancreatic main duct and opened to the ampulla of Vater. b Contrast-enhanced computed tomography scan showing a 12-mm hypervascular mass near the ampulla of Vater and the dilated main pancreatic duct. c Injection of contrast through the minor papilla revealing the dilated dorsal pancreatic duct. d Endoscopic ultrasonography showing a defined hypoechoic mass in the minor papilla with no invasion

Fig. 2

Endoscopic retrograde cholangiopancreatography showing an irregular mucosal surface in the minor papilla

Fig. 3

The largest tumor diameter was 25 × 15 mm in the cross-sectioned specimen, and the tumor was located in the minor papilla

Fig. 4

Histologically, there was infiltration of trabecular tumor with central round nuclei, coarse-clustered chromatin, abundant granules in the cytoplasm, and a low-to-intermediate N/C ratio (×200)

Fig. 5

Immunohistochemical staining showing that chromogranin and synaptophysin were positive