Dermatofibrosarcoma protuberans (DFSP) is an uncommon exophytic, slow growing, low grade, spindle cell tumour arising in the dermal and subcutaneous tissues, particularly of the trunk region with excellent outcome after complete surgical resection.
The tumour occurs in patients of all ages, with the highest frequency occurring between ages 20-50 years. Males are slightly more commonly affected than females.
It typically arises in the dermis as a multi-nodular mass, which then spreads into the subcutaneous tissues and muscle. Lesions ranging from 1 cm to more than 25 cm have been described in the literature.
The trunk is the most common site of involvement, accounting for almost half of all cases. The extremities followed by the head and neck are the next most common sites.
Patients often ignore these tumours because of their slow growth and they are often left untreated for many years.
The typical appearance is that of an unmineralised, nodular soft-tissue mass involving the skin and subcutaneous adipose tissue.
Ultrasound may show a round (67%) or ovoid lesion in the subcutaneous region. Most lesions have well defined margins and a mildly lobulated border. Internal echotexture tends to be heterogeneously hypoechoic matrix, often with rounded, ovoid, or occasionally linear discrete hypoechoic areas. Very small echogenic foci (<0.5 mm), usually without an accompanying comet tail artifact may be seen. Posterior acoustic enhancement is commonly seen. Most tumours show moderate vascularity on colour Doppler imaging. This vascularity tends to be more profound peripherally rather than centrally, and tends to be more organised rather than being chaotic in distribution.
CT may also show a solitary, mostly well defined, mass lesion in the subcutaenous region. Following contrast administration, enhancement is most commonly homogeneous and rarely heterogeneous 3.
Larger lesions (>5 cm) may show intratumoural non-enhancement areas, which could indicate intratumoural areas of necrotic and cystic degeneration.
- T1: low signal
- high signal
- usually higher than or equal to adjacent subcutaneous fat
- fat saturation sequences: suppressed
- T1 C+ (Gd): enhances
Treatment and prognosis
Dermatofibrosarcoma protuberans has an excellent prognosis after complete resection but has a marked tendency to recur locally if inadequate surgical resection margins are obtained. Metastases are rare, most commonly to the lungs.
History and etymology
It was originally described as a distinct clinicopathologic entity in 1924 by Darier and Ferrand. The term “dermatofibrosarcoma protuberans” was coined by Hoffman in 1925 3.
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