Endoscopic mucosal resection of a glomus tumour of the duodenum

Glomus tumours (GT) are proliferative lesions originating from the mesenchymal tissue of glomus bodies, which are arteriovenous shunts involved in thermoregulation of the subungual zones of the fingers and toes [1, 2]. These tumours are rare, accounting for less than 2% of all soft-tissue tumours [2]. Glomus bodies are even rarer in the visceral organs, including the gastrointestinal tract [3]. Female predominance is seen in this tumour epidemiology, and it usually occurs in the fifth or sixth decade of life [1, 2].
The stomach is the most common site of GT in the gastrointestinal tract [4]. The most common presentation is gastrointestinal bleeding, although many cases might be discovered as an incidental finding during upper endoscopy. Endoscopically they are seen as subepithelial lesions, which may resemble carcinoid tumours or gastrointestinal stromal tumours (GIST) among others [5]. Immunohistochemistry (IHC) should be done for definite diagnosis of GT [2, 4]. Most gastric GT are benign, but rare events of malignant transformation have been reported [4]. Although duodenal GT have been reported in the past, they are considered very rare [6].
A hypertensive and otherwise healthy 57-year-old man presented with a history of recent-onset epigastric pain and post-prandial dyspepsia. Upper GI endoscopy revealed a round subepithelial lesion in the second part of the duodenum, and endoscopic ultrasound (EUS) showed the lesion in the second part of the duodenum, measuring about 12 × 7 mm with mixed echo appearance, originating from submucosa, with well-defined borders, and without penetrating to other layers. No surrounding lymph node was detected.
Endoscopic mucosal resection was done by applying a rubber band at the base of the lesion and resection with a hot snare. The resected tissue was retrieved with a basket. Histological evaluation of the lesion showed a round submucosal mass consisting of dilated blood vessels lined by normal endothelial cells and surrounded by a solid proliferation of round cells with perfectly round nuclei and acidophilic cytoplasm. There was no mitosis or atypia (Figure 1). Immunohistochemically, the duodenal tumour cells stained positive for smooth muscle actin (SMA) and vimentin and were negative for chromogranin, C-kit, desmin, cytokeratin, HMB45, Melan-A, and S100, with low proliferative index confirming the diagnosis of GT of the duodenum. Post-resection clinical and endoscopic evaluation at 6, 12, 24, and...


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