Dermatofibrosarcoma protuberans

Synonyms

DFSP

Epidemiology

Rare tumor, but on the skin the most frequent sarcoma type, panethnic, 1:100.000/ year, male:female ratio 1:1,5, mean age around 40 years. Children mostly not affected.

Definition

Dermatofibrosacoma protuberans ( DFSP) is a rare usually non metastizing mesenchymal malignant tumor with an undermining-infiltrative ,aggressive growth pattern and high local recurrence rate.

Aetiology & Pathogenesis

The cause of DFSP is unknown, but a traumatic initiation is discussed. A trauma has been reported in about 10-20% of cases. In 90 % of cases a translocation of genetic material 17q22; 22q13 with fusion of genes COL1A1 and PDGFß has been detected. The gen product, a COL1A1-PDGFß- fusion protein binds to a constitutive expressed PDGF-receptor acting thereafter as an autocrine growth stimulus for DFSP-cells. It usually does not metastasize (< 1%), however, it is highly agressively growing horizontally in the sorrounding , therefore classified as G2.

Signs & Symptoms

DFSP arises from deeper layers of the dermis. Typically, at the beginning no subjective symptoms are reported. DFSP appears solitary and starts starts as a small, firm skin coloured patch and may turn into purplish, reddish, or flesh-colored and is usually without clear margins. A rare variant is pigmented. The tumor grows slowly and infiltrative horizontally and polycyclic but becomes later a plaque and /orclassical derma a big node. At late stage it can exulcerate.

Localisation

It is commonly found on the trunc, usually in the shoulder and chest area.

Classification

Dermatofibrosarcoma protuberans, cassical type.
Bednar-tumor, pigmented type.
Myxoid type.
Pleomorphic – storiform type.

Laboratory & other workups

None specific.

Dermatopathology

The biopsy is essential to diagnose the tumor. For the diagnosis one needs a representative tart piece like biopsy, a punch biopsy is usually less helpful. By low power magnification one can see a the whole dermis infiltrating mesenchymal tumor composed of bundles of spindle cells. A fascicular and radiary growth produces the typical cartwheel pattern. Infiltrating the subcutis produces a honey comb pattern with large bundles of tumor cells sorrounding the adipose cells. By immunohistochemistry the tumor cells express the CD 34 antigen.

Course

A regular follow-up is essential after tumor removal to monitor for recurrence. Local relapses appear in 10-20% of DFSP`s, usually within three years of the initial surgery. Despite being locally aggressive, the tumor spreads to other parts of the body (metastasizes) in only 5% of cases.

Complications

Infiltration with joint involement, exulceration. Scarring.

Diagnosis

Diagnosis relies on clinical features and dermpathology.

Differential diagnosis

Nodular basal cell carcinoma.
Dermatofibroma incl. giant type.
Keloid.
Pleomorphic sarcomas, nodular B-cell lymphoma, pigmented or non-pigmented malignant melanoma (spindle cell type).

Prevention & Therapy

Treatment depends on size and localization. Typically, it is treated with complete wide surgical excision of > 3 cm (lowest recurrence rate of 7%); Mohs surgery or 24 hrs dermpath finding is performed dependent on localisation.

The chemotherapeutic agent imatinib mesylate is approved for adults with unresectable, recurrent, or metastatic dermatofibrosarcoma protuberans.

Special

None.

3.3.9 Dermatofibrosarcoma protuberans