Pathology of Fibrous
This is a common dermal tumour which usually occurs on the extremities in young adults.
Fibrous histiocytoma is regarded as a neoplastic lesion by some authors and an inflammatory or reactive process by others.
Gross: These are usually solitary round or ovoid firm nodule, less than 1cm in diameter.
Aneurysmal variant may be upto 10 cms in diameter. Dark brown or red in colour.
Cream or yellowish cut surface is noted in tumour with abundant lipid.
Dermatofibroma may be associated with melanocytic lesions.
Dermatofibroma may occur in patients associated with HIV infection.
Read the article: Alves JVP, Matos DM, Barreiros HF, Bártolo EAFLF. Variants of dermatofibroma - a histopathological study . Anais Brasileiros de Dermatologia. 2014;89(3):472-477. doi:10.1590/abd1806-4841.20142629.
- Fibrocollagenous : Mainly collagen and fibroblast like cells in irregular or whorled pattern.
- Storiform: Prominent storiform pattern. These are often termed fibrous histiocytoma.
- Lipidized : Presence of numerous foam cells.
- Angiomatous: Presence of small branching vessels in a collagenous stroma. Hemosiderin may be present.
- Aneurysmal Variant:
Differential Diagnosis: Metastatic renal cell carcinoma, xanthogranulomatous reactions, balloon cell naevus / melanoma and clear cell sarcoma.
Further reading: Clear cell dermatofibroma ;
- Cholesterotic associated with hyperlipoproteinemia: Cholesterotic fibrous histiocytoma. Its association with hyperlipoproteinemia.
- Granular cell:
Further reading: Granular cell dermatofibroma;
Dermatofibroma with granular cells: a report
of two cases.
Atypical bizarre cells with foamy cytoplasm, hyperchromatic nuclei.
Further reading: Giant dermatofibroma with monster cells.
Dermatofibroma with monster
Further reading: Dermatofibroma with osteoclast-like giant cells.
Further reading: Ossifying dermatofibroma with osteoclast-like giant cells.
- Myxoid: Stromal mucin is present. (Differential diagnosis: Cutaneous myxoma).
Further reading: Myxoid dermatofibroma on a great toe: a case report.
- With smooth muscle: Smooth-muscle proliferation in dermatofibromas.
Further reading: Palisading subcutaneous fibrous histiocytoma.
- Atrophic :
Further reading: The atrophic dermatofibroma: a delled dermatofibroma.
Differential diagnosis :
Atrophic variants of
dermatofibroma and dermatofibrosarcoma protuberans.
Dermatofibroma extending into
the subcutaneous tissue. Differential diagnosis from
Cellular Fibrous Histiocytoma
Characteristic features of cellular variant:
- Extends into the subcutis
- Mitotic figures are present.
- Central necrosis may be present in some cases.
- Lesion may recur, if incompletely excised.
- Focal smooth muscle actin positive in 60% cases. CD34 is negative
Differential diagnosis - Dermatofibrosarcoma protuberans
|Atypical Cutaneous Fibrous
This is a variant of cutaneous fibrous histiocytoma (dermatofibroma).
Usually presents in middle-aged patients as small nodules occurring on the trunk, limbs , head, neck and vulva.
Histologically these are primarily dermal lesions.
Superficial involvement of the subcutis may occur.
The degree of pleomorphism varied from only focal and minimal or moderate to marked.
Number of mitotic figures ranged from 1 to 15 per 10 high power fields.
Similar to the cellular and aneurysmal variants of fibrous histiocytoma, atypical fibrous histiocytoma shows a higher tendency to recur locally than ordinary fibrous histiocytoma and may rarely metastasize.
Differential diagnosis: Pleomorphic sarcoma ; Atypical fibroxanthoma ; Malignant Fibrous Histiocytoma.
|Differential diagnosis of
CD34+ or +/- ; Factor XIIIa negative, monomorphic population of cells, irregularly infiltrative at the periphery, honeycomb pattern of infiltration into the subcutis).
- Scar ;
- Keloid ;
- Some Hemangiomas;
- Sclerotic Fibroma;
- Dermal Dendrocytoma;
Metastasizing fibrous histiocytoma of
the skin: a clinicopathologic and immuno- histochemical analysis of
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