Duodenal Gangliocytic Paraganglioma: A Rare Neuroendocrine Tumor

Abstract

Gangliocytic paragangliomas, predominantly found in the second part of duodenum, are rare, usually benign tumors with occasional lymph node metastasis. Clinical presentation varies from incidental finding upon endoscopy, or abdominal pain and upper gastrointestinal bleeding. A 73-year old woman with past medical history of non-Hodgkin's lymphoma, presented with intermittent post-prandial epigastric pain, radiating to right upper quadrant, without any weight loss or melena. Physical examination was unremarkable. Laboratory analysis was normal. Cross-sectional imaging of abdomen revealed a possible duodenal diverticulum. Esophagogastroduodenoscopy revealed 17mm, sessile polyp in second part of duodenum. Endoscopic ultrasound (EUS) showed a hypoechoic mass, measuring 17mm x 13mm, extending from mucosa to submucosa and having well-defined margins. EUS-guided fine needle aspiration (FNA) cytology was consistent with a neuroendocrine tumor with immunohistochemical stains positive for synaptophysin, chromogranin and CD56 antibodies. A decision was made to proceed with endoscopic mucosal resection (EMR) which revealed a hypoechoic intramural lesion, appearing to originate from submucosa, overlaid by focal ulcerating flattened duodenal mucosa. The pathology was remarkable for variable admixture of bundles of spindle cells, clusters of ganglion cells and epithelial cells. Immunohistochemical stains showed positive S100 protein in the spindle cells; the epithelioid cells were positive for synaptophysin and CD56 consistent with neuroendocrine differentiation; and the ganglion cells positive for calretinin. Gangliocytic paragangliomas, first reported by Dahl et al. in 1957, is a peculiar neuroendocrine tumor thought to be derived from neural crest with 88% reported lesions located in the second part of duodenum. These tumors are benign and consist of variable admixture of spindle cells, epithelioid cells, and ganglion cells. Rare malignant cases have been reported with regional lymph node metastasis. The epithelioid component was found to be present in the patients with lymph node metastasis; the causal relationship of which is unclear. Due to the submucosal location of the tumor, diagnosis is difficult on endoscopic biopsy which emphasizes the role of EMR in the diagnosis. As most of these tumors are benign and non-functional, EMR is therefore the treatment of choice especially in cases in which the tumor may be removed in its entirety with negative margins.Figure: A 17mm x 13mm, hypoechoic intramural lesion, appearing to originate from submucosa.Figure: Duodenal mass showing variable admixture of ganglion cells, spindle cells, and epithelioid cells (arrow shows ganglion cell). H&E X 100.Figure: Well-controlled immunostain with antibody to synaptophysin shows strong positivity for epithelioid cells. Synaptophysin X 100.