Major and Minor Duodenal Papilla Neuroendocrine Tumors in Type 1 Neurofibromatosis: Case Report

A case of neuroendocrine neoplasm of the minor duodenal papilla

A 61-year-old woman was referred to our hospital for intraductal papillary mucinous neoplasm with no symptoms. Magnetic resonance imaging (MRI) depicted a 15 mm nodular lesion at the descending portion of duodenum. Upper gastrointestinal endoscopy showed a submucosal tumor-like mass at the minor duodenal papilla. A boring biopsy of the tumor revealed a neuroendocrine neoplasm (NEN). Various blood hormone tests were all within normal limits, and the tumor was considered to be nonfunctional. Contrast-enhanced computed tomography showed no obvious distant metastasis, and subtotal stomach-preserving pancreaticoduodenectomy (SSPPD) was performed. Histopathological examination revealed a dense cluster of spindle-shaped cells forming a sheet-like foci and areas showing glandular lumen formation, and immunohistochemistry showed synaptophysin ( + ), chromogranin ( + ). Mitotic rate was about 11 mitoses per 2 square millimeters, Ki-67 index was about 0.2%. She was pathologically diagnosed with NEN G2 at the minor duodenal papilla with regional lymph node metastasis according to the WHO2010 classification. The patient has been currently under outpatient observation with a good postoperative course. Review of the literature identified 43 cases of NENs of the minor duodenal papilla. NENs of the minor duodenal papilla have a high rate of lymph node metastasis, even if the tumor size is small.

Neuroendocrine Tumors (NETs) of the Minor Papilla/Ampulla: Analysis of 16 Cases Underlines Homology With Major Ampulla NETs and Differences From Extra-Ampullary Duodenal NETs

Neuroendocrine tumors (NETs) of the minor papilla/ampulla (MIPA) are rare and poorly studied. Only individual case reports and no comprehensive analysis are available from the literature. We collected 16 MIPA NETs and investigated their clinicopathologic and immunohistochemical features, including markers such as somatostatin, pancreatic polypeptide, gastrin, serotonin, MUC1, cytokeratin 7, and somatostatin receptors type 2A and 5. The median age at diagnosis was 57.5 years, and the female-to-male ratio was 2.2:1. The median NET size was 1.45 cm, and most (94%) were low-grade (G1) tumors. Similarly to what was observed in the major ampulla, 3 histotypes were found: (i) ampullary-type somatostatin-producing tumors (ASTs, 10 cases), characterized by somatostatin expression in most tumor cells, focal-to-extensive tubulo-acinar structures, often with psammoma bodies, MUC1 reactivity, and no or rare membranous reactivity for somatostatin receptor type 2A; (ii) gangliocytic paragangliomas (3 cases), characterized by the coexistence of 3 tumor cell types: epithelioid, often reactive for pancreatic polypeptide, ganglion-like cells, and S100 reactive sustentacular/stromal cells; and (iii) ordinary nonfunctioning NETs (3 cases), resembling those more commonly observed in the extra-ampullary duodenum. Comparable histotypes could also be recognized among the 30 MIPA NETs from the literature. No NET-related patient death among MIPA cases was observed during a median follow-up of 38 months; however, MIPA ASTs showed lymph node metastases and invasion of the duodenal muscularis propria or beyond in 44% and 40% of cases, respectively. In conclusion, MIPA NETs closely resemble tumors arising in the major ampulla, with predominance of ASTs.