Glomus tumor of the stomach: cytologic diagnosis by endoscopic ultrasound-guided fine-needle aspiration.

The glomus tumor is usually a benign solitary neoplasm that arises from modified smooth muscle cells of the glomus body, a type of neuromyoarterial receptor that plays a role in the regulation of arterial blood flow. We report a case of gastric glomus tumor diagnosed by endoscopic ultrasound-guided fine-needle aspiration. Smears exhibited groups of cohesive, uniform, small, round to polygonal cells with scant cytoplasm, indistinct cell borders, and round, hyperchromatic nuclei with homogeneous chromatin. The cell block contained fragments of cells with similar morphologic features and immunohistochemical staining exhibited positivity for smooth muscle actin and vimentin. The diagnosis was confirmed by the surgically resected specimen. Ultrastructural examination revealed prominent pinocytotic vesicles lining the plasmalemma. In this report, we discuss the differential diagnosis of gastric glomus tumor and compare the cytologic features of this case with two others reported in the literature.