Soft tissue tumors - Glomus tumor

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Soft tissue tumors

Normal / benign

Glomus tumor

Reviewer: Vijay Shankar, M.D. (see Reviewers page)
Revised: 25 February 2013, last major update November 2012
Copyright: (c) 2003-2013, PathologyOutlines.com, Inc.

See also symplastic

General
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● 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+ only OR deep only

Glomangiosarcoma:
● Deep (to muscular fascia) and 2 cm or larger OR 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
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● 24 year old man with glomus tumor of cheek (Case Report Med 2012;2012:307294)
● 44 year old man with painful lesion in plantar region (An Bras Dermatol 2011;86:1029)
● 47 year old man with glomangiosarcoma of shoulder (dermpathMD)
● 50 year old woman with primary glomus tumor of liver (Indian J Pathol Microbiol 2011;54:584)

Clinical images
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Thumb #1

Index finger

Plantar nodule

Gross description
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● Less than 1 cm, rounded, red-blue, yellowish to tan red, firm
● Resembles fresh hemorrhage under the nail

Gross images
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Liver tumor

Micro description
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● 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

Micro images
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Index finger tumor

Thumb

Liver

Cheek is benign but invades vessel wall	Plantar nodule is SMA+
Glomangiosarcoma of shoulder

Cytology description
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● 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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Round to oval cells with homogenous granular chromatin

Positive stains
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● Smooth muscle actin, type 4 collagen, vimentin
● CD34 in 20% only
● Variable expression of h-caldesmon and calponin

Negative stains
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● Cytokeratin, desmin, S100, chromogranin

Electron microscopy description
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● Resemble smooth muscle cells

Symplastic glomus tumor

General
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● High nuclear grade but no mitotic figures or other features of malignancy; may be degenerative

Case reports
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● 78 year old male with nail deformity of indx finger (J Cutan Pathol 2009;36:1099)
● 81 year old man with mass in subcutis of great toe (Case of Week #238)

Micro images
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(a) multiple foci of glomus cells surrounding capillary-sized vessels in myxoid stroma with some nerve fibers and bone
(b) glomus cells show prominent cytological atypia with nuclear enlargement and pleomorphism, anisonucleosis, hyperchromasia, pseudoinclusions, bizarre nuclei, coarse chromatin, and irregular nuclear membrane

Images from Case of the Week #238:



CD34	Ki-67	Smooth muscle actin	Vimentin	Desmin

End of Soft tissue tumors > Normal / benign > Glomus tumor

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