# Dermatofibrosarcoma protuberans

Source: https://onco.cc/cancers/dermatofibrosarcoma-protuberans/  
OnCo record `dermatofibrosarcoma-protuberans` (Cancer). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Dermatofibrosarcoma protuberans is a rare, slow-growing cancer of the deeper skin that usually appears as a firm plaque or lump on the trunk and is often mistaken for a scar or cyst for years. Surgery with wide margins cures most people; for the few whose tumour cannot be removed or has spread, the pill imatinib works because almost every one is driven by a single gene fusion it blocks.

## Summary

Dermatofibrosarcoma protuberans is a low-grade sarcoma of the dermis and subcutis driven in more than nine in ten cases by a translocation fusing COL1A1 to PDGFB, which places the platelet-derived growth factor B gene under a collagen promoter and creates an autocrine loop through the PDGFRB receptor. It presents as a slowly enlarging, indurated plaque or nodule, most often on the trunk or proximal limbs, that infiltrates far beyond its visible edge along fibrous septa. About one in ten tumours contains a fibrosarcomatous component, which raises the recurrence and metastatic risk; metastasis, mostly to lung, otherwise occurs in fewer than one in twenty patients. The pigmented Bednar variant and the giant cell fibroblastoma of children are related tumours with the same fusion.

Surgery is the treatment: wide excision with 2 to 3 centimetre margins to fascia, or Mohs micrographic surgery or its slow variant with paraffin sections, which lets the surgeon trace the finger-like extensions and gives the lowest recurrence rates. Recurrence is a function of margin status, so re-excision of involved margins is standard, and radiotherapy is added when clear margins cannot be achieved at sites such as the head and neck. Fibrosarcomatous tumours are followed with imaging for lung metastases.

Imatinib, which inhibits PDGFRB, produced responses in about half of the 24 patients with unresectable or metastatic disease in the pooled EORTC 62027 and SWOG S0345 phase 2 trials, and was approved for unresectable, recurrent or metastatic dermatofibrosarcoma protuberans in October 2006, one of the first uses of a targeted drug chosen by a fusion. It is also given before surgery to shrink large or awkwardly placed tumours and reduce the defect. Fusion-negative tumours do not respond, so confirming the COL1A1-PDGFB fusion by FISH or sequencing is required before treatment; sunitinib and pazopanib have activity after imatinib failure, and fibrosarcomatous or metastatic disease may need sarcoma-type chemotherapy.

## Fields

- Kind: Cancer
- Last checked: 2026-09-17
- Also known as: DFSP; Bednar tumour (pigmented dermatofibrosarcoma protuberans); Fibrosarcomatous dermatofibrosarcoma protuberans
- Tags: subtype-page
- Group: skin
- Burden: Dermatofibrosarcoma protuberans is a rare sarcoma of the skin, about four cases per million people a year, commonest in adults aged 20 to 50 and roughly twice as common in Black people; it is slow-growing and rarely spreads, but it recurs locally if not excised with wide margins.
- Subtypes: Classic dermatofibrosarcoma protuberans (DFSP; low grade, dermal and subcutaneous); Fibrosarcomatous DFSP (higher grade, higher recurrence and metastatic risk); Bednar tumour (pigmented DFSP); Giant cell fibroblastoma (childhood variant with the same fusion); Unresectable, recurrent or metastatic DFSP (imatinib candidates); Fusion-negative DFSP (does not respond to imatinib)
- Biomarkers: COL1A1-PDGFB fusion by fluorescence in situ hybridisation or sequencing (required before imatinib); CD34 positivity and factor XIIIa negativity on immunohistochemistry; Fibrosarcomatous component on histology; Margin status after excision; Rare alternative PDGFD fusions in fusion-negative cases

## Standard of care

- Localised disease: Wide local excision with 2 to 3 cm margins to fascia, or Mohs micrographic surgery with complete circumferential margin assessment; re-excision for involved margins. ([Mohs surgery](https://onco.cc/terms/mohs-surgery/), [Wide local excision](https://onco.cc/terms/wide-local-excision/))
- Positive margins not amenable to further surgery: Adjuvant radiotherapy to the tumour bed. ([IMRT / IGRT (modern external beam)](https://onco.cc/technologies/imrt-igrt/))
- Unresectable, recurrent or metastatic disease: Imatinib after confirming the COL1A1-PDGFB fusion (EORTC 62027 and SWOG S0345); surgery after response where feasible. ([Imatinib](https://onco.cc/drugs/imatinib/), [PDGFRB](https://onco.cc/targets/pdgfrb/))
- Neoadjuvant: Imatinib for several months to shrink large or facial tumours before excision. ([Imatinib](https://onco.cc/drugs/imatinib/))
- After imatinib failure or fibrosarcomatous metastatic disease: Sunitinib or pazopanib; sarcoma-type chemotherapy with doxorubicin for metastatic fibrosarcomatous disease. ([Sunitinib](https://onco.cc/drugs/sunitinib/), [Pazopanib](https://onco.cc/drugs/pazopanib/), [Doxorubicin](https://onco.cc/drugs/doxorubicin/))

## State of the art

- Wide excision or Mohs surgery cures the great majority, and margin-controlled surgery has cut recurrence rates sharply.
- Imatinib, chosen by the COL1A1-PDGFB fusion, gives responses in about half of unresectable or metastatic tumours and can make surgery possible.
- Fusion testing separates responders from the rare fusion-negative tumours that need other treatment.

## Open problems

- Diagnosis is delayed for years because the tumour looks like a scar, keloid or cyst.
- Responses to imatinib are not permanent and the drugs after it have only small series behind them.
- Fibrosarcomatous transformation is the cause of most deaths and has no specific therapy.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Dermatofibrosarcoma_protuberans
- Imatinib in DFSP, pooled EORTC and SWOG trials (JCO 2010): https://ascopubs.org/doi/10.1200/JCO.2009.25.9899
- Wikipedia: https://en.wikipedia.org/wiki/Dermatofibrosarcoma_protuberans

## Connected records

- cancers: [Kaposi sarcoma](https://onco.cc/cancers/kaposi-sarcoma/), [Sarcomas (soft tissue, bone, GIST)](https://onco.cc/cancers/sarcoma/)
- terms: [Mohs surgery](https://onco.cc/terms/mohs-surgery/), [Rare cancers](https://onco.cc/terms/rare-cancers/), [Wide local excision](https://onco.cc/terms/wide-local-excision/)
- technologies: [IMRT / IGRT (modern external beam)](https://onco.cc/technologies/imrt-igrt/), [Small-molecule kinase inhibitors](https://onco.cc/technologies/kinase-inhibitors/)
- targets: [PDGFRA](https://onco.cc/targets/pdgfra/), [PDGFRB](https://onco.cc/targets/pdgfrb/)
- drugs: [Doxorubicin](https://onco.cc/drugs/doxorubicin/), [Imatinib](https://onco.cc/drugs/imatinib/), [Pazopanib](https://onco.cc/drugs/pazopanib/), [Sunitinib](https://onco.cc/drugs/sunitinib/)

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