Dermatologic Manifestations of Glomus Tumor Workup

Updated: Apr 04, 2019
  • Author: Vernon J Forrester, MD; Chief Editor: Dirk M Elston, MD  more...
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Laboratory Studies

Routine laboratory studies are not helpful in patients with glomus tumors. The rare exception is in patients with widely disseminated lesions in which platelet sequestration is a concern. In these patients, a complete blood cell count is indicated.


Imaging Studies

While the diagnosis of a glomus tumor is often made based on clinical presentation and histologic findings, imaging may prove useful, [52] especially in cases in which the diagnosis is in doubt. Imaging can also be useful in planning for excision.

Plain radiography has been reported to reveal bony erosions, especially in the case of subungual lesions; however, radiography may not be sensitive in a large percentage of cases. [53] Ultrasonography, especially color-duplex ultrasonography, has a high detection rate and no false-negative results, at least in one series; additionally, ultrasonography can detect glomus tumors as small as 2 mm. [54, 55, 56] Ultrasound may be a particularly useful tool for exploring tumors involving the nail, with glomus tumors often visualized as small, solid, hypoechoic or isoechoic nodules with hypervascularity on Doppler. [57] In one study, glomus tumors were excised from a number of patients with a solitary symptom of cold sensitivity and with only positive imaging findings on ultrasound (vs no findings on CT/MRI). [58]

MRI has also been studied and may be particularly useful for the detection of multiple tumors [59, 60] or in cases in which the diagnosis or specific location of the lesion is in question. [30] High-resolution MRI has proven useful as well [53, 61] and can be particularly helpful in delineating the relationship of subungual tumors to surrounding structures during pretreatment planning. [62] Mundada et al provide a detailed review of nail tumors and the use of MRI in diagnosis and management. [62]


Histologic Findings

Solitary glomus tumors and glomuvenous malformations (GVMs) have distinct histopathologic features. The World Health Organization classifies glomus tumors based on their predominance of glomus cells, vascular structures, and smooth muscle cells as solid glomus tumors (most common, glomus cell prominence), glomangioma (vascular cell prominence), and glomangiomyoma (vascular and smooth muscle cell prominence).

Solitary lesions appear mostly as solid, well-circumscribed nodules surrounded by a rim of fibrous tissue. They contain endothelium-lined vascular spaces surrounded by clusters of glomus cells. The glomus cells are monomorphous, round or polygonal cells with plump nuclei and scant eosinophilic cytoplasm. Note the images below.

Glomus tumor (4X). The tumor is composed of unifor Glomus tumor (4X). The tumor is composed of uniformly round, small, glomus cells with pale eosinophilic cytoplasm associated with conspicuous vasculature.
Glomus tumor (10X). Glomus tumor (10X).

GVMs, formerly known as glomangiomas, are less well circumscribed and less solid appearing than their solitary counterparts. Multiple lesions have the overall appearance of a hemangioma. They contain multiple irregular, dilated, endothelium-lined vascular channels that contain red blood cells. The vascular spaces are larger than those in a solitary glomus tumor. Small aggregates of glomus cells are present in the walls of these channels and in small clusters in the adjacent stroma. Multiple glomus tumors have more narrow and focal aggregates of glomus cells than solitary lesions. The overall appearance of multiple glomus tumors accounts for their alternate name, glomangiomas. Note the images below.

Glomangioma (2X). In this variant, blood vessels p Glomangioma (2X). In this variant, blood vessels predominate.
Glomangioma (10X). Note the typical small, round g Glomangioma (10X). Note the typical small, round glomus cells, often distributed in a monolayer or bilayer within the vessel walls.

Glomangiosarcomas (malignant glomus tumors) resemble benign glomus tumors. However, glomangiosarcomas have more atypia, pleomorphism, and mitotic figures, and they have a locally invasive growth pattern. Most often, malignant lesions are correlated with foci of benign glomus tumor. However, glomangiosarcomas may also arise de novo.

While glomus cells can be epithelioid in appearance, they are immunoreactive with markers for a-smooth muscle actin (aSMA), muscle-specific actin (MSA), and h-caldesmon. Glomus tumors also have abundant type IV collagen. These markers can be useful in distinguishing glomus tumors from hemangiomas. It is also important to note that glomus tumors are distinct from paragangliomas, which are positive for S100. [3, 20]