LAUSR

A 59-year-old, otherwise medically healthy, lady presented with a 3-day history of melaena. She was haemodynamically stable and biochemistry was unremarkable. Gastroscopy revealed a 15 × 20 mm submucosal mass with ulceration and bleeding in the second portion of the duodenum. Endoscopic ultrasound characterized a uniformly hypoechoic oval-shaped subepithelial lesion in the medial duodenal wall. Cytological examination of the fine-needle aspiration biopsy showed a triphasic morphology, with epithelioid cells, spindle cells and ganglion-like cells. Subsequent three-phase computed tomography scan characterized a 17 × 17 × 20 mm arterially enhancing luminal duodenal mass with normal arterial and venous anatomy, as well as a 12-mm right subpectoral lymph node. The mass was not avid on dotatate Ga68 scan, but was avid on 18-fluorodeoxyglucose positron emission tomography. There was no evidence of tumour spread. The patient underwent pancreaticoduodenectomy with pancreaticojejunostomy, hepaticojejunostomy and gastrojejunostomy. The unencapsulated tumour was relatively well circumscribed, and there was no macroscopic evidence of metastatic disease, with clear margins on the superior mesenteric artery and vein (Figs 1,2). Final histological examination revealed a 20 × 20 × 20 mm tumour, 20 mm proximal to the ampulla. Upon microscopic analysis, the tumour was pathognomic for gangliocytic paraganglioma (GP) – triphasic morphology with an admixture of epithelioid cells, ganglion cells and spindle cells (Fig. 3). There was characteristic positive staining for synaptophysin in the epithelioid cells and ganglion cells; positive staining for chromogranin and neurofilament protein (NFP) in the ganglion cells; and NFP and S100 in the spindle cells. Sixteen lymph nodes showed only non-necrotizing granulomatous inflammation. The patient made an uneventful recovery, and remains disease free on follow-up. GPs are a rare subclass of duodenal neuroendocrine neoplasm, arising in proximity to the major duodenal papilla of Vater. According to the World Health Organization classification of gastrointestinal neuroendocrine tumours (NETs), duodenal GPs are classified as low-grade NETs, based on their mitotic activity and Ki-67 proliferation index. However, there is an argument that GPs should be classified as an independent entity based on their clinical behaviour and better prognosis. The GP is characterized by its triphasic cellular differentiation: epithelioid neuroendocrine cells, spindle cells with Schwann cell differentiation and ganglion cells, all of which were identified on endoscopic ultrasound with fine needle biopsy (EUS-FNA) in this case. The epithelioid cells resemble welldifferentiated NETs or paraganglioma in both cytologic and architectural features, and are generally positive for neuroendocrine markers such as synaptophysin and chromogranin, and are frequently positive for keratins. The spindle cells resemble those seen in peripheral nerve sheath tumours, and are generally positive for S100. The ganglion-like cells have characteristic abundant cytoplasm and prominent nucleoli, and are positive only for synaptophysin. These cell components can vary in distribution and proportion within the tumour itself, and upon diagnosis, care must be taken to biopsy multiple regions, so as to not sample a heterogeneous region and misdiagnose the GP as a well-differentiated NET, gastrointestinal stromal tumour, paraganglioma, leiomyoma or schwannoma. EUS-FNA was undertaken as tissue diagnosis confirms the diagnosis, with immunohistochemical examination (progesterone receptor and pancreatic polypeptide), allowing for identification of GP even on small biopsy specimens.