[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Skin](https://durgical.com/en/general-pathology/areas/skin/) › Dermatofibroma vs dermatofibrosarcoma protuberans

# Dermatofibroma vs dermatofibrosarcoma protuberans

- Lesion

Dermatofibroma is a common harmless firm bump. Dermatofibrosarcoma protuberans looks similar early on but keeps growing and comes back if not fully removed.

Updated Nov 12, 2026

## Key points

- Dermatofibroma: firm tan-brown papule; dimple sign when pinched; overlying epidermal hyperplasia; collagen trapping at the edges; factor XIIIa positive, CD34 negative.
- DFSP: slowly growing plaque that becomes nodular (protuberant), on the trunk; storiform (cartwheel) spindle cells infiltrating fat in a honeycomb pattern; CD34 positive.
- DFSP genetics: t(17;22) COL1A1-PDGFB fusion, often in a ring chromosome; constant PDGF receptor stimulation.
- Imatinib blocks the PDGF receptor and is used for unresectable DFSP.
- Fibrosarcomatous transformation of DFSP increases metastatic risk.

## What it is

Dermatofibroma is a benign, often reactive, fibrohistiocytic nodule, typically on the legs of young and middle-aged adults, sometimes after minor trauma such as an insect bite. Dermatofibrosarcoma protuberans is a low-grade sarcoma of the dermis and subcutis driven by a COL1A1-PDGFB fusion; it infiltrates widely, recurs locally and rarely metastasises.

## Dermatofibroma vs DFSP

| Feature | Dermatofibroma | Dermatofibrosarcoma protuberans |
| --- | --- | --- |
| Behaviour | Benign | Low-grade sarcoma, local recurrence |
| Site | Legs | Trunk, proximal limbs |
| Depth | Dermis, limited | Dermis into fat (honeycomb) |
| Pattern | Haphazard fascicles, collagen trapping | Uniform storiform |
| Epidermis | Hyperplasia, basal pigment | Thinned, uninvolved |
| Markers | Factor XIIIa positive, CD34 negative | CD34 positive, factor XIIIa negative |
| [Genetics](https://durgical.com/en/conditions/soft-tissue-sarcomas/) | Clonal in some, usually none specific | COL1A1-PDGFB fusion |

## Clinical notes

- DFSP needs wide or Mohs excision with clear margins.
- Dermatofibroma needs no treatment unless the diagnosis is uncertain.

## Memory aid

Dermatofibroma dimples when pinched and stays put; DFSP spins a cartwheel (storiform) and rolls into the fat.

## Test yourself

Think of the answer, then tap the question to see it.

## Which fusion drives dermatofibrosarcoma protuberans?

COL1A1-PDGFB, from t(17;22), often in a ring chromosome.

## Which immunostain separates DFSP from dermatofibroma?

CD34 is positive in DFSP and negative in dermatofibroma (which is factor XIIIa positive).

## Why does imatinib work in DFSP?

The fusion produces excess PDGF-B, and imatinib blocks the PDGF receptor tyrosine kinase.

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## Elsewhere in DurgiPedia

- [Translocations, amplifications and epigenetic changes in cancer](https://durgical.com/en/general-pathology/translocations-amplifications-and-epigenetic-changes-in-cancer/)
- [Immunohistochemistry: the principle and the markers to know](https://durgical.com/en/general-pathology/immunohistochemistry-the-principle-and-the-markers-to-know/)

## Connections

## Related 3

- [Skin pathology: terms and reaction patterns](https://durgical.com/en/general-pathology/skin-pathology-terms-and-reaction-patterns/)
- [Translocations, amplifications and epigenetic changes in cancer](https://durgical.com/en/general-pathology/translocations-amplifications-and-epigenetic-changes-in-cancer/)
- [Abnormal repair: chronic wounds, hypertrophic scar, keloid, contracture](https://durgical.com/en/general-pathology/abnormal-repair-chronic-wounds-hypertrophic-scar-keloid-contracture/)

## Related conditions 2

- [Soft tissue sarcomas (liposarcoma, leiomyosarcoma, rhabdomyosarcoma)](https://durgical.com/en/conditions/soft-tissue-sarcomas/)
- [Keloid and hypertrophic scar](https://durgical.com/en/conditions/keloid-and-hypertrophic-scar/)

[← All of general pathology](https://durgical.com/en/general-pathology/)

Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Dermatofibrosarcoma protuberans](https://medlineplus.gov/genetics/condition/dermatofibrosarcoma-protuberans/) (MedlinePlus, US National Library of Medicine, 2025).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/general-pathology/dermatofibroma-vs-dermatofibrosarcoma-protuberans/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/dermatofibroma-vs-dermatofibrosarcoma-protuberans/