[5] Histologically, glomus tumors are made up of an afferent arteriole, anastomotic vessel, and collecting venule.

As stated above, these lesions should not be confused with paragangliomas, which were formerly also called glomus tumors in now-antiquated clinical usage.

Familial glomangiomas have been associated with a variety of deletions in the GLMN (glomulin) gene, and are inherited in an autosomal dominant manner, with incomplete penetrance.

[10] A few cases of cancerous glomus tumors have been reported; however, they are usually only locally invasive, and metastases are exceedingly rare.

There is one report of widespread metastases of a malignant glomus tumor involving the skin, lungs, jejunum, liver, spleen, and lymph nodes.

[10] The probable misdiagnosis of many of these lesions as hemangiomas or venous malformations also makes an accurate assessment of incidence difficult.