[Gastrointestinal glomus tumors: a clinicopathological analysis of fifteen cases].

Objective: To investigate the clinicopathological features, diagnosis and differential diagnosis of gastrointestinal glomus tumors (GIGT). Methods: Totally 15 cases of GIGT were collected at the First Affiliated Hospital, Zhengzhou University, from January 2011 to June 2018. The clinicopathological features, immunophenotype, BRAF V600E mutation and prognosis were retrospectively analyzed. Results: The 15 patients' age ranged from 37 to 59 years(median 49 years, mean 50 years). Eleven patients presented with intermittent abdominal pain and distention, three showed antral space-occupying lesions at physical examination, and one had abdominal pain accompanied by fecal blood. Fourteen tumors were located in the stomach, and one was in the ileum. Imaging showed the gastric glomus tumors were located in the submucosal layer with obvious enhancement in the arterial phase, and the ileum glomus tumor involved the whole layer of intestinal wall causing luminal obstruction. The maximum diameters of the tumors ranged from 1.5 to 3.0 cm (mean 2.3 cm). Grossly, the gastric glomus tumors were solid. Microscopically, the gastric glomus tumors were mostly located in the muscularispropria layer and were vascular. The tumor boundary was distinct but without capsule formation. The tumor cells were round or oval, and showed perivascular hemangiopericytoma-like or solid nest-like structures. The tumor cells were mildly pleomorphic, with rare mitosis and no necrosis. Two tumors had focal calcification, two showed mucosal invasion, two showed vascular invasion and five showed perineural invasion. The ileum glomus tumor was cellular, with prominent cellular atypia, and the mitotic count in hot spots was about 5-6/HPF. Immunohistochemistry showed that SMA and collage were strongly expressed in all the tumor cells; caldesmon and calponin were moderately expressed in some regions, and syn was weakly expressed in 12 cases. The Ki-67 proliferation index in the gastric glomus tumors ranged from 1% to 30% (mean 6%); and that in the ileum glomus tumor was about 70%. BRAF V600E mutations were not detected in any of 15 GIGTs. All patients did not receive radiotherapy or chemotherapy post operatively. Thirteen patients were followed up by telephone for 18-90 months (mean 42 months). Twelve patients with gastric glomus tumors survived without recurrence and metastasis, and the patient with ileum glomus tumor had liver metastasis 15 months after operation. Conclusions: Glomus tumors is a rare mesenchymal tumor of the gastrointestinal tract. It should be differentiated from gastrointestinal stromal tumors, neuroendocrine tumor, leiomyoma, solitary fibrous tumor and paraganglioma. Most GIGTs are benign and have good prognosis. More experience is needed to understand the biologic behavior and prognostication of GIGTs.