Gastric glomus tumor: clinical conundrums and potential mimic of gastrointestinal stromal tumor (GIST)

Abstract

Gastric glomus tumor is a rare neoplasm of the gastrointestinal tract that frequently mimics other mesenchymal lesions clinically and radiologically. We present a 70-year-old woman with an incidentally detected submucosal tumor of the antrum that was thought to be a gastrointestinal stromal tumor (GIST). The lesion measured 1.9 cm radiographically and was monitored over a period of 3 years. Multiple biopsies were attempted but did not yield a clear diagnosis. Over time, the lesion increased in size and developed an area of ulceration, prompting a wedge resection. After surgery, a diagnosis of glomus tumor was reached on the basis of histological and immunohistochemical studies. Glomus tumors are neoplasms of perivascular smooth muscle differentiation that can occur nearly anywhere in the body but exhibit a strong predisposition for the skin and subcutaneous tissue. They usually follow an indolent clinical course, although rare cases of metastasis have been reported. Gastrointestinal involvement is uncommon, and when present, the stomach is almost exclusively involved. Preoperative diagnosis may be impossible given the overlapping features with other mesenchymal tumors of the stomach, as illustrated in our case. A literature review of 210 gastric glomus tumors is provided, and important diagnostic pitfalls are highlighted to prevent misdiagnosis. In an era of precision medicine where incidental lesions are increasingly detected by routine endoscopy and imaging, awareness of this rare entity is important, as gastric glomus tumors are generally benign with a favorable prognosis following complete resection.

Keywords: GIST; Glomus tumour; gastrointestinal stromal tumour; mesenchymal tumor; stomach.

Figure 1

Gastric glomus tumor. A. These generally present as a circumscribed intramural mass that arises in the muscularis propria and frequently mimics a gastric GIST clinically and radiologically. B. Overlying mucosal ulceration is noted in about 27% of cases and can result in significant gastrointestinal bleeding. C. At scanning magnification, gastric glomus tumors exhibit a multinodular appearance. D. The classic morphology of small uniform round cells proliferating around vascular channels is virtually diagnostic of this entity. E. In keeping with their smooth muscle origin, gastric glomus tumor cells show strong, intense and diffuse smooth muscle actin immunoreactivity. Pathogenetically, they are thought to arise from the neuromyoarterial canals (i.e. glomus bodies) which are responsible for thermoregulation. F: Normal glomus body from skin.