Glomus Tumour
Epidemiology and Etiology:
Common sites:
- Skin or
superficial soft tissues (almost always)
- Distal extremities
(vast majority)
- Subungual particularly
- Hand
- Wrist
- Foot
- (GI sites):
Gross features:
- small (<1cm)
typically
- red-blue cutaneous nodules
- painful,
particularly with exposure to cold or minor tactile stimulation
- multiple in 10%
- GI tract:
- Circumscribed
- Mural mass
bulging either way
- ulcerated
- May be calcified
Histologic features:
- Cells closely resemble
the modified smooth muscle cells of the normal glomus
body
- Small
- Uniform
- Rounded
- Central round
nucleus
- Amphophilic to lightly eosinophilic
cytoplasm
- Each cell
surrounded by basal lamina (PAS / toluidine
blue)
- Typical glomus tumours:
- Solid glomus tumour (75%)
- Nests of glomus cells surrounding capillary sized vessels
- Stroma may be hyalinized
or myxoid
- small cuffs of glomus cells often seen around small vessels
located outside the main mass
- Glomangioma (most common type when multiple or
familial)
- Dilated veins
surrounded by small clusters of glomus cells
- Glomangiomyoma
- Transition from
typical glomus cells to elongated cells
resembling mature smooth muscle
- May have a
solid or glomangioma-like architecture
- May have hemangiopericytoma-like vasculature (“glomangiopericytoma”)
- May see:
- Oncocytic change
- Epithelioid change
- GI tract:
- Multinodular; nodules separated by strands of
residual muscularis propria
- Ulcerated
- Sheets of cells
surrounding gaping hemangiopericytoma-like
vessels
- Tumour cells present in muscular walls of
larger vessels
- Cells are round
with sharply defined cell membranes
- Perfectly
rounded nuclei
- Delicate
chromatin
- Not mitotically active
- Glomangiomatosis:
- Symplastic glomus tumour:
- Striking nuclear
atypia in absence of any other worrisome
feature
- Malignant glomus tumour (exceedingly
rare):
- Any one of the
following:
- Size >2cm
and subfascial or visceral location
- Atypical mitotic
figures
- Marked nuclear atypia and any level of mitotic activity
- 2 types:
- resembling leiomyosarcoma or fibrosarcoma
- overall
architectural similar to benign glomus tumour
- necrosis is also
worrisome
- glomus tumour of
uncertain malignant potential:
- at least one
atypical feature other than nuclear pleomorphism
- not fulfilling
above criteria for malignancy
Immunophenotype:
Marker:
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Sensitivity:
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Specificity:
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SMA
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Calponin
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h-caldesmon
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Type IV collagen (pericellular, abundant)
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Desmin (neg)
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Laminin or collagen type IV (pericellular net-like pattern)
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CD117 (neg)
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Keratin (neg)
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S100 (neg)
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Molecular features:
Other features:
- EM – modified
smooth muscle cells
- benign (vast
majority)
- GI tract lesions:
- severe bleeding
presenting with melena often
- malignant glomus tumours are exceedingly rare (<1%)
- association
between subungual glomus
tumours and NF1
References:
- Gastrointestinal
and Liver Pathology 2005
- WHO Soft Tissue and
Bone 2002