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This is a distinctive
benign fibrous soft tissue tumour that was first described by Evans in
1995.
Clinical presentation:
The lesion presents as a firm, well circumscribed, painless mass of long
duration and are commonly located in the subcutaneous tissue or skeletal
muscle in adults. The tumours range in size from 1 to 20 cm.
Site:
This entity has been reported
in various locations, including the upper extremities, posterior neck,
upper back, lower extremities, abdominal wall, and hip.
Gross: Macroscopically,
the lesion presents as an elongated, lobulated, or disc-shaped mass with a
firm consistency and a homogeneous grayish-white colour.
Microscopic features:
Image1 ;
Image2
The tumour is relatively hypocellular. There is proliferation of bland
spindle or stellate shaped cells embedded in a fibromyxoid to densely fibrotic collagenous
stroma. The stroma may contain a large amount of mucin which
is positive with alcian blue.
Mitotic figures are very
rare or absent, tumour necrosis is not seen, and vascularity is low.
The tumour often focally
infiltrate the surrounding skeletal muscle and adipose tissue.
Immunohistochemistry:
Diffusely positive for vimentin.
In some cases there
may be focal staining for
smooth muscle actin.
S-100, EMA , CD34, desmin and keratin are usually negative.
Electron microscopy :
Revealed features consistent with a fibroblastic or
myofibroblastic lineage.
Differential diagnosis:
Fibromatosis- Collagenous fibroma should be
differentiated from fibromatosis, which has a high risk of local
recurrence if simple local excision is done. Fibromatosis is more
cellular and shows short fascicular arrangements of tumour cells and
greater infiltration at the periphery than collagenous fibroma.
Neurofibroma;
Nodular fasciitis ; Fibroma
of tendon sheath
;
Solitary fibrous tumour;
Perineurioma
;
low-grade fibromyxoid sarcoma.
Summary of the clinical, radiographic, and
pathological characteristics of the tumors in the differential for
collagenous fibroma
(Sarcoma.
2009;
2009:
682687.)
The tumour did not recur
after complete surgical excision.
Visit:
Desmoplastic Fibroblastoma (Stanford)
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