Soft tissue
Benign vascular tumors
Glomus tumor

Author: Vijay Shankar, M.D.

Revised: 31 January 2018, last major update November 2012

Copyright: (c) 2003-2018,, Inc.

PubMed search: Glomus tumor [title] soft tissue

Related topics: Symplastic glomus tumor

Cite this page: Shankar, V. Glomus tumor. website. Accessed November 20th, 2018.
Definition / general
  • Usually benign; excision curative
  • Occurs in wide age range
  • Subungual tumors are exquisitely painful due to abundant nerve fibers
  • Arises from modified smooth muscle cells of glomus body, a specialized arteriovenous anastomosis involved in thermoregulation
  • Usually under fingernails; also skin, flexor arm / knee, GI tract, rarely in head and neck
  • All glomus tumors should have at least focal areas of typical glomus tumor, usually at periphery (Am J Surg Pathol 2001;25:1)
  • Glomangioma:
    • Glomus tumors that resemble cavernous hemangiomas
  • Glomangiomatosis:
    • Diffuse angiomatosis resembling angiomatosis with excess glomus cells
    • Often associated with considerable fat and pain
    • Probably represents vascular malformations
  • Glomangiomyoma:
    • Combines features of glomus tumor and angioleiomyoma
  • Glomus tumor of uncertain malignant potential: high (5+ / 50 HPF) mitotic activity and superficial OR 2 cm+ OR deep
  • Glomangiosarcoma: atypical mitotic figures OR moderate / high nuclear grade and 5+ MF / 50 HPF
    • 38% had metastases in one series, no metastases in symplastic, uncertain malignant potential, glomangiomatosis
Case reports
Clinical images
Images hosted on PathOut server:

Mammogram, courtesy of Dr. Mark R. Wick

Multifocal, face, courtesy of Dr. Mark R. Wick

Third toe, courtesy of Dr. Mark R. Wick

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Fullness in posterior nail fold region

Glomus tumor during exploration

Gross images
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Liver tumor

Microscopic (histologic) description
  • Branching vascular channels separated by stroma containing glomus cells in nests, aggregates
  • Glomus cells are arranged around vessels
  • Have small, regular, round, indistinct nucleoli
  • More infiltrative in children
  • May have secondary myxoid change
  • Very low mitotic activity
Microscopic (histologic) images
Images hosted on PathOut server:

Breast, courtesy of Dr. Mark R. Wick

Case of the Week #289:

Forearm mass

Alpha-smooth muscle actin


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Cheek is benign but invades vessel wall

Glomangiosarcoma of shoulder

Vessels of varying sizes

Relationship of glomus cells to the vessels

Solid areas w/ organoid growth pattern

Collars of glomus cells

Sheet of uniform tumor cells

Cytology description
  • Cohesive clusters of uniform round cells with scanty cytoplasm
  • Background of scattered amorphous magenta colored material, blood and occasional inflammatory cells (J Cytol 2010;27:104)
Cytology images
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FNA of breast, courtesy of Dr. Mark R. Wick

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Positive stains
Negative stains
Electron microscopy description
  • Resemble smooth muscle cells