Glomus tumor

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2] Roukoz A. Karam, M.D.[3]

Glomus body was first discovered by Wood, a Scottish surgeon, in 1812 in the Edinburgh Medical Journal. However, Glomus tumor was first correctly described in 1924 by Barre and Masson. Glomus tumor arises from modified smooth muscle cells (or pericytes) of the glomus body (previously called as glomus cells). Glomus tumors may be classified into solitary and multiple variants. On gross pathology, they are small (usually less than 1 cm), bluish or whitish, well circumscribed, solitary nodules are characteristic findings of glomus tumor. On microscopic histopathological analysis, branching vascular channels and aggregates of specialized glomus cells are characteristic findings of glomus tumor. Multiple glomus tumors are caused by a mutation in the GLMN (glomulin) gene. Solitary glomus tumors must be differentiated from other diseases that cause pain such as leiomyoma and eccrine spiradenoma. Multiple glomus tumors must be differentiated from other diseases such as cavernous hemangioma and blue rubber bleb nevus syndrome. Solitary glomus tumors commonly affect young to middle aged individuals. Multiple glomus tumors commonly affect children. Females are more commonly affected with solitary glomus tumors (particularly subungual lesions) than males. Males are more commonly affected with multiple glomus tumors than females. Common risk factors in the development of glomus tumors are age and gender. If left untreated, patients with glomus tumors may progress to develop pain and nail discoloration. Common complication of the glomus tumor includes malignant change in multiple tumors. Common complications of glomus tumors post operatively include nail deformities and recurrence. Findings on x rays suggestive of glomus tumor may include a marginated bone erosion or thinning of the adjacent cortical bone. MRI and ultrasound may be helpful in the diagnosis of glomus tumors. Surgery is the mainstay of treatment for glomus tumor. Prognosis is generally excellent for solitary glomus tumors and malignant glomus tumors treated with wide excision. However, the prognosis is poor for malignant glomus tumors with widespread metastases.

Glomus body was first discovered by Wood, a Scottish surgeon, in 1812 in the Edinburgh Medical Journal. However, Glomus tumor was first correctly described in 1924 by Barre and Masson.

Glomus tumors may be classified into solitary and multiple variants.

Glomus tumor arises from modified smooth muscle cells (or pericytes) of the glomus body (previously called as glomus cells). The glomus body is a neuromyoarterial plexus in the dermis of skin that is normally involved in thermoregulation. The gene involved in the pathogenesis of familial glomangioma is the glomulin (GLMN) gene. On gross pathology, small (usually less than 1 cm), bluish or whitish, well circumscribed, solitary nodules are characteristic findings of glomus tumor. On microscopic histopathological analysis, branching vascular channels and aggregates of specialised glomus cells are characteristic findings of glomus tumor.

The cause of solitary glomus tumors has not been identified. Multiple glomus tumors are caused by a mutation in the GLMN (glomulin) gene.

Solitary glomus tumors must be differentiated from other diseases that cause pain such as leiomyoma and eccrine spiradenoma. Multiple glomus tumors must be differentiated from other diseases such as cavernous hemangioma and blue rubber bleb nevus syndrome.

The exact incidence of glomus tumors is unknown. Females are more commonly affected with solitary glomus tumors (particularly subungual lesions) than males, while multiple lesions are slightly more common in males. Solitary glomus tumors can occur at any age; however, multiple glomus tumors commonly affect children.

There are no established risk factors for glomus tumor; however, an epidemiologic relationship may exist between glomus tumors and neurofibromatosis.

Screening for multiple glomus tumors by genetic testing is recommended among individuals with a family history of glomangiomas (autosomal dominant inheritance).

If left untreated, patients with glomus tumors may progress to develop pain and nail discoloration. Common complication of the glomus tumor includes malignant change in multiple tumors. Common complications of glomus tumors post operatively include nail deformities and recurrence. Prognosis is generally excellent for solitary glomus tumors and malignant glomus tumors treated with wide excision. However, the prognosis is poor for malignant glomus tumors with widespread metastases.

There is no single diagnostic study of choice for the diagnosis of glomus tumor, but glomus tumors can be diagnosed based on MRI of the finger in addition to history and physical examination.

A detailed history from the patient may be helpful. A positive history of trauma may be present. A positive family history may be present in patients with multiple glomus tumors (autosomal dominant). Symptoms of glomus tumor include hypersensitivity to cold and paroxysmal pain at a well defined site.

Patients with glomus tumor usually appear well. Physical examination of patients with glomus tumor is usually remarkable for small (usually less than 2cm), blue or red palpable nodules which are usually distributed in the acral regions (subungual most common) and nail deformities.

There are no diagnostic laboratory findings associated with glomus tumor.

There are no ECG findings associated with glomus tumor.

X rays may be helpful in the diagnosis of glomus tumor. Findings on x rays suggestive of glomus tumor may include a marginated bone erosion or thinning of the adjacent cortical bone.

Ultrasound may be helpful in the preoperative diagnosis of glomus tumor; it provides the localization, size, and shape of tumors as small as 3 mm. Findings on an ultrasound suggestive of glomus tumor include a well-circumscribed hypoechoic mass.

There are no CT findings associated with glomus tumors.

An MRI may be helpful in the diagnosis of glomus tumor. Findings on MRI suggestive of glomus tumor include slightly hypointense or hyperintense T1 images and hyperintense T2 images.

There are no other imaging findings associated with glomus tumor.

Other diagnostic studies for glomus tumor include immunohistochemistry staining, which demonstrates glomus cells positive for vimentin and alpha-smooth muscle actin and negative for desmin.

The predominant therapy for solitary glomus tumor is surgical resection. Patients with multiple glomus tumors are treated with sclerotherapy or laser therapy.

Surgery is the mainstay of treatment for glomus tumor.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Roukoz A. Karam, M.D.[2]

Glomus body was first discovered by Wood, a Scottish surgeon, in 1812 in the Edinburgh Medical Journal. However, Glomus tumor was first correctly described in 1924 by Barre and Masson.

Glomus tumor was first described by Wood, a Scottish surgeon, in 1812 in the Edinburgh Medical Journal.^[1][2]

• However, Wood described it as a small, bluish, benign, subcutaneous nodule associated with severe paroxysmal pain and tenderness.
  • He called this lesion a “painful subcutaneous tubercle.”
• In 1878, Kolaczek described the subungual location of a painful tubercle, which he believed to be a variant of angiosarcoma.
• Glomus tumor was first correctly described by Barre and Masson in 1924.^[1][2]
  • They correctly interpreted the pathologic anatomy of the painful tubercle.
  • Barre and Masson called it a glomus tumor because of its relationship to the normal neuromyoarterial glomus.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2]

Glomus tumors may be classified into solitary and multiple variants.

Glomus tumors may be classified into the following:^[1]

• Solitary glomus tumors
  • Mostly encapsulated and subungual
• Multiple glomus tumors
  • More common in children
  • Mostly non-encapsulated and may occur anywhere in the body, rarely subungual
  • Multiple glomus tumors may be classified further into the following:^[1][2][3]
    • Localized
    • Segmental
    • Disseminated
    • Plaque-like glomus tumours
      • Congenital and very rare

Glomus tumors may be classified according to histopathology into the following subtypes:^[4][5]

• Solid glomus tumor (most common variant-75%)
  • Poor vasculature and scant smooth muscle components
• Glomangioma (20%)
  • Prominent vascular component
• Glomangiomyoma (5%)
  • Prominent vascular and smooth muscle components

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2]

Glomus tumor arises from modified smooth muscle cells (or pericytes) of the glomus body (previously called as glomus cells). The glomus body is a neuromyoarterial plexus in the dermis of skin that is normally involved in thermoregulation. The gene involved in the pathogenesis of familial glomangioma is the glomulin (GLMN) gene. On gross pathology, small (usually less than 1 cm), bluish or whitish, well circumscribed, solitary nodules are characteristic findings of glomus tumor. On microscopic histopathological analysis, branching vascular channels and aggregates of specialized glomus cells are characteristic findings of glomus tumor.

• Glomus tumor arises from modified smooth muscle cells of the glomus body (or glomus apparatus). The glomus body consists of an arterio-venous shunt surrounded by a capsule of connective tissue.
• The glomus body is a neuromyoarterial plexus located in the stratum reticulare, that is normally involved in thermoregulation. Although the glomus tumors are mostly concentrated in the digits, they are distributed throughout the body.^[1]
• Glomus tumors should not be confused with paragangliomas which arise from glomus cells and were previously called glomus tumors.

• Familial glomangioma is a variant of glomus tumor where the patient presents with multiple glomus tumors.^[2]
• The gene involved in the pathogenesis of familial glomangioma is glomulin (GLMN) gene.^[2]
  • Mutations are associated with multiple deletions in the glomulin gene of chromosome 1p21-22.^[2]
  • Inheritance is autosomal dominant with incomplete penetrance.^[2]

• Glomus tumors of the fingers and toes may be associated with neurofibromatosis type 1.^[3][4]

• Solitary glomus tumors appear as small reddish-gray encapsulated masses 0.1 to 0.3 cm in diameter.^[5]
  • May reach 3 cm
• Multiple glomus tumors are usually less circumscribed and less solid than the solitary glomus tumors.^[2]

• On microscopic histopathological analysis, characteristic findings of glomus tumor include:^[6][7]
  • Polygonal cells with moderately distinct cellular borders
  • Round to oval nuclei
  • Striking eosinophilic cytoplasm
  • Inconspicuous to well-defined nucleoli
  • Aggregates of specialized glomus cells
  • Thin-walled, branching vascular channels with bland endothelial cells
  • Tumor cells identified immediately adjacent to the endothelial cells
  • No apparent mitotic activity
  • Focal nuclear enlargement is present; however, no significant nuclear atypia is identified.

• 
  Intermediate magnification micrograph of a glomus tumor. H&E stain.Source: wikimedia commons^[8]
• 
  High magnification micrograph of a glomus tumor. H&E stain.Source: wikimedia commons^[8]
• 
  Very high magnification micrograph of a glomus tumor. H&E stain.Source: wikimedia commons^[8]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2]

The cause of solitary glomus tumors has not been identified. Multiple glomus tumors are caused by a mutation in the GLMN (glomulin) gene.

• The exact cause of solitary glomus tumors has not been identified. However, trauma may cause a weakening in the structure of the glomus body, resulting in reactive hypertrophy.^[1]
• Multiple glomus tumors are caused by a loss of function mutation in the GLMN (glomulin) gene.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2]

Solitary glomus tumors must be differentiated from leiomyoma and eccrine spiradenoma. Multiple glomus tumors must be differentiated from other diseases such as cavernous hemangioma and blue rubber-bleb nevus syndrome.

The presence of pain in most cases means the differential diagnosis must include other painful tumors that can occur in the digits:^[1]

• Neuroma
• Eccrine spiradenoma
• Leiomyoma
• Ganglion
• Exostosis
• Causalgia
  • Complex regional pain syndrome type 2
• Gouty arthritis
• Calcinosis
• Solitary glomus tumors must be differentiated from the following:^[2]
  • Leiomyoma
  • Eccrine spiradenoma
• Multiple glomus tumors must be differentiated from other diseases such as:^[2][3][4]
  • Cavernous hemangioma
  • Blue rubber-bleb nevus syndrome
• Glomus tumors must also be differentiated from the following:^[4]
  • Blue nevi
  • Dermatologic manifestations of Kaposi sarcoma
  • Dermatologic manifestations of schwannoma
  • Maffucci syndrome
  • Solid and cystic hidradenoma
  • Myopericytoma
  • Myofibromatosis (myofibroma)
  • Angiosarcoma
  • Dermatofibroma
  • Capillary hemangioma

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2]

The exact incidence of glomus tumors is unknown. Females are more commonly affected with solitary glomus tumors (particularly subungual lesions) than males, while multiple lesions are slightly more common in males. Solitary glomus tumors can occur at any age; however, multiple glomus tumors commonly affect children.

• The exact incidence of glomus tumors is unknown.
• Glomus tumors account for 1-5% of all soft-tissue tumors of the upper extremity, occurring in most cases in the nail bed.^[1]
• The true incidence of glomus tumors could be even higher, likely as a result of misdiagnosis of many of these lesions as hemangiomas or venous malformations.
• An epidemiologic relationship may exist between glomus tumors and neurofibromatosis, which most often produces subungual glomus tumors.^[2][3]

• Solitary glomus tumors can occur at any age.^[4]
  • While previously thought to occur predominantly in young adults between the ages of 20 and 40 years, they have also been reported to be frequent in older adults between 40 and 70 years of age.
• Multiple glomus tumors commonly affect children.
  • Multiple glomus tumors develop 11–15 years earlier than single lesions.
  • One third of the cases of multiple glomus tumors affect individuals younger than twenty years of age.

• Females are more commonly affected with solitary glomus tumors (particularly subungual lesions) than males.^[5]
• Multiple lesions are slightly more common in males.^[6]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Roukoz A. Karam, M.D.[2]

There are no established risk factors for glomus tumor; however, an epidemiological relationship may exist between glomus tumors and neurofibromatosis.

• There are no established risk factors for glomus tumor; however, an epidemiological relationship may exist between glomus tumors and neurofibromatosis.^[1]
• A strong association between type I neurofibromatosis and glomus tumors has been identified. In neurofibromatosis patients with glomus tumors, the sex distribution, tumor location, and tumor burden appear similar to those in patients with isolated glomus tumors.^[2]
• It is strongly recommend that one should suspect a glomus tumor in patients with neurofibromatosis type 1 if such patients have symptoms from finger pulp or nails.^[3]

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2]

Screening for multiple glomus tumors by genetic testing is recommended among individuals with a family history of glomangiomas (autosomal dominant inheritance).

• Screening for multiple glomus tumors by genetic testing is recommended among individuals with a family history of glomangiomas (autosomal dominant inheritance).^[1]
• Screening for genetic mutations in the glomulin gene helps in the diagnosis of approximately 70% of the patients with familial glomangiomas.^[1]

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Soujanya Thummathati, MBBS [2]

If left untreated, patients with glomus tumors may progress to develop pain and nail discoloration. A common complication of the glomus tumor is malignant change in multiple tumors. Common complications of glomus tumors post operatively include nail deformities and recurrence. Prognosis is generally excellent for solitary glomus tumors and malignant glomus tumors treated with wide excision. However, the prognosis is poor for malignant glomus tumors with widespread metastases.

If left untreated, patients with glomus tumors may progress to develop pain and nail discoloration.^[1]

• A common complication of the glomus tumor is malignant change in multiple glomus tumors (glomangiosarcomas).
  • Very rare and usually only locally invasive
  • Widespread metastases may occur which are fatal
• Common complications of glomus tumors post operatively include:^[1]
  • Nail deformity
  • Recurrence
    • Recurrence is thought to be a result of incomplete excision or, in the case of late recurrence, development of a new lesion at or near the excision site. Excision of the capsule of the tumor is required to prevent local recurrence.^[2]
• Glomus tumors may recur locally:^[3]
  • 10% of cases
  • Usually infiltrative lesions
• Malignant glomus tumors are exceptional and include:^[4]
  • Glomus tumors showing marked nuclear atypia along with any mitotic activity
  • Glomus tumors containing atypical mitotic figures

Prognosis is generally excellent for solitary glomus tumors and malignant glomus tumors treated with wide excision.

However, the prognosis is poor for malignant glomus tumors with widespread metastases.^[5]

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