Gastric glomus tumors are considered rare, but the clinical presentation of these tumors has been well documented.1-8Despite this documentation, we could not find one report in the literature that included their clinical presentation, preoperative endoscopic and biopsy findings, preoperative radiologic imaging findings, operative management, and histologic characteristics. In our report on the case of a gastric glomus tumor in a 33-year-old woman, we discuss each of these topics and provide a brief review of the literature.
A 33-year-old woman who was 5 weeks postpartum presented to the emergency department of an urban Colorado teaching hospital. She had been experiencing dizziness, weakness, coffee-ground emesis, and melena. Her hemato?crit was 17.8%. After the patient was stabilized, an esophagogastroduodenoscopy was performed. Her esophagus appeared normal until the scope was advanced through the esophagogastric junction to the antrum, where a 2-cm, well-circumscribed, exophytic mass was observed (Figure 1). Several biopsies were taken from the mass.
Histologically, the tumor was composed of a proliferation of uniform round cells with centrally placed, darkly staining nuclei, and a small amount of clear to eosinophilic cytoplasm (Figure 2). The tumor cells were arranged around vascular spaces, which were lined by bland endothelial cells. There was no evidence of significant cytologic atypia, and mitotic figures were not seen. Im?mun?o?histochemical staining for smooth muscle actin and vimentin were strongly positive, while cytokeratin, chromogranin, and c-Kit (CD117) were not detected (Figure 3). The histologic appearance and immunohistochemical profile of the mass in our patient supported the diagnosis of a glomus tumor. Preoperative computed tomography (CT) scanning revealed a subtle, hypodense, intraluminal mass in the prepyloric region measuring 2.9 cm (Figure 4). There were no inflammatory changes or significant adjacent adenopathy. Because frozen-section diagnosis during surgery may not allow glomus tumors to be differentiated from other smooth muscle tumors, it is beneficial to diagnose a benign glomus tumor of the stomach preoperatively. A rare tumor such as this can present a diagnostic dilemma, and every possible step in the diagnostic armamentarium should be utilized. Immunohistochemical staining is the most sensitive and specific tool for diagnosing these tumors and is often necessary to make a definitive diagnosis. Because immunohistochemical staining takes 1 to 2 hours to complete, stains available for use during an operation are limited. Given the rarity of the tumor, the diagnostic dilemma faced, and the logistics and timing of making the diagnosis, preoperative diagnosis is vital so that more extensive surgery can be avoided.
Based on our preoperative diagnosis, the patient was taken to the operating room and explored through a midline incision with plans to proceed with localized excision of the tumor. The tumor was visualized along the greater curvature of the stomach in the region of the pylorus. It did not appear to penetrate through the wall of the stomach, and no enlarged lymph nodes were detected. A limited distal gastrectomy and gastroduodenostomy were performed.
On gross pathology examination, a gelatinous, dark red, ulcerated mass was identified on the mucosal surface of the antrum, which extended to a depth of 3.5 cm. The tumor was histologically identical to that of the previous biopsy specimen. Although there was tumor within the muscularis propria, it did not extend to the serosal surface. The proximal and distal margins were clear. The two included lymph nodes showed only reactive changes.
Glomus tumors are mesenchymal tumors made up of modified muscle cells arising from glomus bodies.7 Glomus bodies are arteriovenous communications that help regulate the body's skin temperature.8 Glomus tumors most commonly occur in the peripheral soft tissues.7 Several cases of glomus tumors of the gastrointestinal tract have been reported, and glomus tumors of the stomach have also been described in the literature, although rarely.1-9 Our review of the literature failed to identify any cases of gastric glomus tumors that were evaluated using all of the diagnostic tools currently available, including eso?phago?gastroduo?denoscopy, CT scanning, and histologic and immunohistochemical staining.
Gastric glomus tumors are generally considered solitary, benign lesions1-8; however, cases of multiple glomus tumors of the stomach and a case of a large glomus tumor of the stomach that metastasized to the liver have been reported.5,7,9 In addition, Folpe and colleagues reported a series of 52 cases of atypical or malignant glomus tumors.9
Clinically, glomus tumors may cause local gastrointestinal irritation, including hemorrhage or even obstruction.1-6 Patients may have melena and abdominal pain. Gastric perforation has also been reported.7 The CT findings of a gastric glomus tumor have been described as peripheral nodular or homogeneous strong enhancement in the arterial phase and prolonged enhancement in the delayed phase.6
Histologically, the main characteristics of glomus tumors are glomus cells and irregular vascular channels.1 Most tumors are composed of multiple cellular nodules that are often separated and surrounded by gastric smooth muscle cells. In addition, a capsule-like rind of connective tissue is often seen on the serosal and mucosal surfaces of the tumor.7The most recent development in the diagnosis of glomus tumors is the use of immunohistochemical staining, which can make an often difficult pathologic diagnosis easier.
Glomus tumors may be confused with other tumors because they appear histologically similar to these lesions, which include gastrointestinal stromal tumors (GISTs), carcinoid tumors, paragangliomas, and lymphomas.7 Historically, differentiating glomus tumors from GISTs has been difficult1,7,9; however, the difference between these tumors is readily apparent with immunohistochemical staining. GISTs almost always stain positive for c-Kit (CD117) and 70% of the time stain positive for CD34. In contrast, glomus tumors are consistently negative for c-Kit and are rarely positive for CD34.7 GISTs are also generally negative for smooth muscle actin, which is almost always positive in glomus tu?mors.7 Carcinoid tumors are differentiated from glomus tumors by their positive staining for cytokeratins such as chromogranin and synaptophysin. These cytokeratins are rarely seen in glomus tumors.7 Paragangliomas, like carcinoid tumors, can be differentiated from glomus tumors by their positivity for chromogranin and synaptophysin.7 Finally, lymphomas (specifically gastric mucosa-associated lymphoid tissue) can be definitively differentiated from glomus tumors by leukocyte-specific markers such as CD20 and CD45.7
The overall immunohistochemical profile of glomus tumors includes positive staining for smooth muscle actin and vimentin. Glomus tumors are negative for c-Kit, cytokeratin, and chromogranin, which generally distinguishes these lesions from GISTs and epithelial cell tumors, such as paragangliomas and carcinoid tumors, respectively (Table). By examining the immunohistochemical profile of a given tumor, a definitive diagnosis can be made.
Gastric glomus tumors are rare and generally benign. By using different diagnostic tools including esophago?gastroduo?denoscopy, CT scanning, and histologic examination (specifically immuno?histo?chemical staining), a correct diagnosis can be made and suitable treatment provided. Benign glomus tumors are treated with focused, local excision.
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8. Park SH, Han JK, Kim TK, et al. Unusual gastric tumors: radiologic-pathologic correlation. Radiographics. 1999;19(6): 1435-1446.
9. Folpe AL, Fanburg-Smith JC, Miettinen M, et al. Atypical and malignant glomus tumors: analysis of 52 cases, with a proposal for the reclassification of glomus tumors. Am J Surg Pathol. 2001;25(1): 1-12.