Case 5 -

Glomus Tumor Nour Sneige University of Texas M.D. Anderson Cancer Center Houston, TX

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Clinical History: A 44-year-old man presented with a longstanding history of pain in the right mid-thigh. After "exploratory surgery" was performed 9 years previously, the patient started noticing a very painful mass under the surgical scar. MRI confirmed the presence of a 3.2-cm mass in close proximity to the femoral vein and artery, and an FNA biopsy was performed. Case 5 - Figure 1 Papanicolaou stain, low power Case 5 - Figure 2 Papanicolaou stain, medium power Case 5 - Figure 3 Papanicolaou stain, medium power Case 5 - Figure 4 Papanicolaou stain, medium power Case 5 - Figure 5 Papanicolaou stain, high power Case 5 - Figure 6 Diff-Quik stain, high power Cytologic Features: The aspirated specimen was cellular and was composed of tight clusters and more loosely cohesive sheets of medium-sized polygonal cells and frequent stripped nuclei. In places, the cell groups formed a three-dimensional pattern. The nuclei were oval to round, with finely distributed chromatin. The cytoplasm was moderate and well defined. A concurrent core needle biopsy specimen showed uniform medium-sized polygonal cells confined by distinct cell borders. The component cells, arranged in nests and broad sheets, had round, centrally placed nuclei surrounded by a moderate amount of eosinophilic cytoplasm. The tumor cells were negative for cytokeratin, S100 protein, chromogranin, and synaptophysin but were strongly positive for smooth muscle actin. The diagnosis of glomus tumor was rendered. Histologic and Clinical Follow-up: The excised mass was well circumscribed and consisted of solid sheets of cells interrupted by vessels of various sizes. Less intricate vasculature with surrounding nests simulating the pattern of paraganglioma was noted, as were myxoid changes in the stroma. Postoperatively, the patients' symptoms of cold intolerance and the burning sensation over his left thigh have completely resolved. Discussion: Glomus tumors arise from modified smooth muscle cells located in the walls of specialized arteriovenous anastomoses (the Sucquet-Hoyer canal) that serve in thermal regulation. These lesions are relatively common and occur most often in young adults; there is no sex predilection except for digital and subungual lesions, which tend to predominate in females. Most tumors are <1 cm in diameter and develop in the dermis or subcutis of the upper and lower extremities, especially in the hands. Cutaneous lesions present as red-blue nodules and may be associated with paroxysmal pain in response to tactile stimulation. Multiple lesions are seen occasionally, most often in children, and most are believed to be inherited in an autosomal dominant fashion (the genetic aberration has been linked to chromosome 1p). Although glomus tumors have a predilection for the skin of the distal fingers and toes, especially under the nails, other reported anatomic sites include bone and joints, skeletal muscle, soft tissue, mediastinum, trachea, lung, liver, kidney, uterus, vagina, bowel, bone, and stomach. Histologically, most glomus tumors are well circumscribed and are composed of various proportions of glomus cells, vascular structures, and smooth muscle tissue. According to their relative proportions, glomus tumors have been divided into three groups: (1) glomangiomas, which are by far the most common, accounting for 60% of glomus tumors, (2) solid glomus tumors (25% of cases), and (3) glomangiomyoma (15%). Depending on the size of the nests of glomus cells, the tumor may have a highly vascular appearance, reminiscent of hemangiopericytoma or paraganglioma, or a cellular appearance, suggestive of an epithelial tumor. The surrounding stroma often appears edematous and can show extensive myxoid degeneration. A rare variant of glomus tumor showing oncocytic change and a variant predominantly composed of epithelioid cells have been described. Glomus tumor cells are typically immunopositive for smooth muscle actin and muscle-specific actin and are occasionally focally positive for desmin. The majority of glomus tumors are entirely benign, and local recurrence is very uncommon. Despite worrying histologic features in occasional cases, glomus tumors (or glomangiosarcoma) are exceedingly rare. In 2001, Folpe et al. proposed a reclassification scheme with criteria based on tumor size, superficial vs. deep location, mitotic activity, and nuclear grade, separating atypical or malignant glomus tumors into malignant, symplastic, glomus tumors of uncertain malignant potential, and glomangiomatosis. A review of the cytology literature reveals that the first reported description of the FNA aspirate characteristics of glomus tumors was in 1996. A total of five other case reports have been published. One axillary mass was misdiagnosed as ectopic breast tumor, and of three gastric glomus tumors, one was misdiagnosed as a neuroendocrine tumor and one as a stromal tumor. Even in histologic sections, glomus tumors are known to masquerade as diverse epithelial growths, such as low-grade malignancies not further specified, metastatic adenocarcinoma, carcinoid tumors, paraganglioma and certain adnexal growths, such as eccrine spiradenoma and hidradenoma. The rarity of these tumors makes their diagnosis challenging, but thoughtful consideration, coupled with immunohistochemical analysis, can lead to the correct diagnosis. Because glomus tumors are generally indolent neoplasms, including those with clinical or histologic features of malignancy, discriminating them from more aggressive neoplasms is important and can avoid unnecessary treatment. References: Debol SM, Stanley M, Mallery S, Sawinski E, Bardales RH. Glomus tumor of the stomach: cytologic diagnosis by endoscopic ultrasound-guided fine-needle aspiration. Diagn Cytopathol 2003;28:316-21. Enzinger FM, Weiss SW. Perivascular tumors. In: Enzinger FM, Goldblum JR, editors. Soft tissue tumors, 4th ed. St. Louis, Mo: Mosby; 2001:985-1003. Folpe AL, Fanburg-Smith JC, Miettinen M, Weiss SW. Atypical and malignant glomus tumors: analysis of 52 cases, with a proposal for the reclassification of glomus tumors. Am J Surg Pathol 2001;251:1-12. Gu M, Nguyen PT, Cao S, Lin F. Diagnosis of gastric glomus tumor by endoscopic ultrasound-guided fine needle aspiration biopsy: a case report with cytologic, histologic, and immunohistochemical studies. Acta Cytol 2002;46:560-66. Handa U, Palta A, Mohan H, Punia RP. Aspiration cytology of glomus tumor: a case report. Acta Cytol 2001;45(6):1073-6. Holck S, Bredesen JL. Solid glomus tumor presenting as an axillary mass: report of a case with morphologic study, including cytologic characteristics. Acta Cytol 1996;40:555-62. Perez-Guillermo M, Sola Perez J, Garcia Rojo B, Hernandez GA. Fine needle aspiration cytology of cutaneous vascular tumours. Cytopathol 1993;3(4):231-44. Vinette-Leduc D, Yazdi HM. Fine-needle aspiration biopsy of a glomus tumor of the stomach. Diagn Cytopathol 2001;24:340-2.