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collagenous fibroma; desmoplastic fibroblastoma
Epidemiology: mostly adults, male predominance.
Clinical manifestations:
- painless, slow growing subcutaneous mass
- wide anatomical distribution, predilection for shoulder & upper limb, often centered around fascial or aponeurotic tissue
Microscopic pathology:
- most have infiltrative margins
- spindle or stellate fibroblasts, sparsely distributed in extensive hyalinized/focally myxoid matrix with few blood vessels
- nuclei ovoid, small nucleoli
- mitoses rare or absent
- no necrosis or cytologic atypia
Immunohistochemistry:
- actin focally +
- keratin rare +
Differential diagnosis:
1) nodular fasciitis
2) fibroma of tendon sheath
General
benign fibroblastic/myofibroblastic neoplasm
References
Fletcher. CTTR 109th Cancer Seminar. Soft Tissue Tumors