Dermatofibrosarcoma protuberans (DFSP) is a low-grade malignant tumor arising from dermal and subcutaneous tissues and is the most common cutaneous sarcoma (although overall still quite rare). It is most commonly found at the trunk and proximal extremities 6.
Its behavior is notable for a high reported rate of local recurrence, although outcomes overall are favorable.
The tumor 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 tumors because of their slow growth and they are often left untreated for many years.
The typical appearance is that of an unmineralized, 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 a 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 tumors show moderate vascularity on color Doppler imaging. This vascularity tends to be more profound peripherally rather than centrally and tends to be more organized rather than being chaotic in distribution.
CT may also show a solitary, mostly well defined, mass lesion in the subcutaneous region. Following contrast administration, enhancement is most commonly homogeneous and rarely heterogeneous 3.
Larger lesions (>5 cm) may show intratumoral non-enhancement areas, which could indicate intratumoral 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.
Fibrosarcomatous variant of dermatofibrosarcoma protuberans (FS-DFSP) is an uncommon and aggressive variant of DFSP, associated with a higher tendency for local recurrence and distant metastasis 8. Wide excision with ≥2 cm margins or Micrographic Mohs surgery with smaller margins is the treatment of choice for FS-DFSP, to avoid local recurrence and metastasis. Radiation has a role in cases with incomplete surgical resection, whereas the PDGFR-inhibitor imatinib is effective in irresectable, locally advanced and metastatic cases 8.
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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