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Age:
Young to middle aged individuals
Site:
Commonly located in the upper limb (fingers) and is usually attached to
the tendon.
Gross:
Well circumscribed, lobulated fibrous nodule. They are firm and rubbery
and on section have a grayish-white appearance.
Microscopic features:
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The lesions consist of a dense fibrocollagenous tissue with a variable
degree of collagenization and cellularity, the peripheral zone often being
most cellular and containing slit-like vascular spaces. In some cases
there may be complete hyalinization. Mitotic activity depends on the
cellularity of the lesion.
Other features:
Presence of inflammatory cells and myxoid stroma in some cases. Rare
presence of giant cells or foamy cells.
Immmunohistochemistry:
Vimentin - Positive ;
muscle-specific actin and smooth muscle actin - Positive.
Desmin - Negative ; Factor XIIIa- Positive ; CD34- Positive ;
CD68 (+/- ).
Cytogenetics:
Transclocation 2;11 has been found in one
case.
Electron-microscopy:
Two main cell
types were identified: Myofibroblasts and fibroblasts, the former
dominating in cellular areas, the latter dominating in collagenized areas.
Differential diagnosis:
Giant
cell tumour of tendon sheath (localised nodular tenosynovitis) ;
Circumscribed fibromatosis ;
Nodular
fasciitis; Neurofibroma
; Leiomyoma ; Scar tissue ;
Benign fibrous
histiocytoma ;
Comparison with Giant cell tumour of
tendon sheath:
This lesion is more common
than fibroma of tendon sheath. Histologically the two tumours have
separate and distinct histologic features. Fibroma of the tendon sheath is
hypocellular, with slit-like vascular channels within a dense
collagen matrix , whereas giant cell tumor of the tendon sheath
is much more cellular and contains multiple multinucleated
giant cells, foamy histiocytes, and hemosiderin.
All cases are
treated effectively by local excision or reexcision of the growth.
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