Glomus Tumors

 Considered to fall on morphologic spectrum with myopericytoma, myofibroma, and angioleiomyoma

Clinical Issues

• Most common in young adults (20-40 years)

• Female predilection in subungual tumors

• Most common in distal extremities (particularly nail bed)

• Typically small, red-blue nodule, often solitary and painful

• Most arise in skin or subcutis

• Treatment: Complete surgical excision

• Excellent prognosis in conventional glomus tumor (GT)

• Malignant GT is clinically aggressive


• Most are < 1 cm in size


• Typically solid nests of round cells closely associated with variably sized blood vessels
image Characteristic centralized, rounded, uniform nuclei

• Hyalinized to myxoid stroma

• No mitotic activity or necrosis

• Variants: Glomangioma, glomangiomyoma, glomangiomatosis, symplastic GT

• Malignant forms exist but are very rare

Ancillary Tests

• SMA(+), caldesmon (+)

• Negative for desmin, S100, keratin, synaptophysin

Top Differential Diagnoses

• Myopericytoma

• Benign adnexal tumors

• Dermal melanocytic nevus

• Paraganglioma

Clinical Photograph of Subungual Glomangioma
This is an example of a subungual glomangioma on the thumb (the nail has been avulsed prior to biopsy image).

Glomus Tumor at Low Magnification
Glomus tumor (GT) is a rare benign tumor that may arise almost anywhere, but shows a predilection for the distal extremities, particularly under the nail bed (subungual). It is histologically characterized by sheets and nests of uniform, round to epithelioid cells arranged around a conspicuous vasculature image.

Monotonous Nuclei in Glomus Tumor
The distinctive nuclei in GT are strikingly monomorphic and feature a sharply defined, round nuclear contour. They are often described as being “punched out.” Cytoplasmic borders vary in prominence, and may be easy or difficult to visualize, depending upon the individual tumor. Mitotic figures are absent.

SMA Expression in Glomus Tumor
Strong, diffuse cytoplasmic expression of SMA is characteristic of GT. Caldesmon is also typically positive. Desmin is negative.



• Glomus tumor (GT)


• Perivascular mesenchymal neoplasm composed of cells closely resembling modified smooth muscle cells of normal glomus body
image Considered to fall on morphologic spectrum with myopericytoma, myofibroma, and angioleiomyoma

• Several morphologic variants exist, including glomangioma (glomuvenous malformation), glomangiomyoma, glomangiomatosis, and symplastic GT


Small Subsets Are Inherited

• Often feature multiple lesions
• Multiple familial GT

image Inactivation of GLMN gene

• Neurofibromatosis type 1 (NF1)
image Biallelic inactivation of NF1 gene



• Incidence
image Rare

– Malignant GT extremely rare

• Age
image Most common in young adults (20-40 years)
– Overall wide age range

– Glomangioma variant more common in childhood

• Sex
image Female predilection in subungual tumors


• Overall wide distribution
• Most common in distal extremities

image Particularly subungual location

• Rarely in other anatomic locations, including visceral organs (particularly GI tract), bone, mediastinum


• Typically small, red-blue nodule, often solitary
image Multiple in up to 10% of cases

– Multifocality also seen within setting of NF1

• Most arise in skin or subcutis
image Rarely in deep soft tissues

• Usually painful
image Long history of pain

image Pain with exposure to cold &/or tactile stimulation


• Complete surgical excision

• Clinical follow-up for malignant GT and GT of uncertain malignant potential


• Excellent prognosis in conventional GT
image < 10% recur locally

image Includes symplastic forms, glomangiomatosis, and other variants

• Malignant GT is clinically aggressive
image Metastases and death of patients in up to 40% of cases

• Large, visceral GT have potential for aggressive behavior regardless of histology


General Features

• Red-blue nodular lesions


• Most are < 1 cm
image Deeper lesions may be larger


Histologic Features

• Well circumscribed ± fibrous pseudocapsule
image Small nests of glomus cells associated with small vessels may be identified around periphery of main tumor

• Typically solid nests of cells within highly vascularized stroma
image Vessels range from small to large and ectatic (staghorn appearance)

image Tumor cells arranged around vessels, often as cuffs

image Diffuse nodular, sheet-like appearance in highly cellular tumors

• Characteristic small, round, uniform tumor cells with pale eosinophilic to amphophilic cytoplasm
image Each cell contains single centralized small, round, uniform nucleus
– Sometimes described as “punched out”

– Absence of nuclear atypia and significant mitotic activity

image Occasionally cases feature oncocytic or epithelioid cytomorphology

image Each cell surrounded by basal lamina

• Hyalinized to myxoid stroma

• No necrosis

• Rare intravascular growth

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Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Glomus Tumors

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