Dermatofibrosarcoma Protuberans (DFSP) is an infrequent type of malignant skin sarcoma. It arises from the dermis of the skin. DFSP accounts for less than 6% of all soft tissue sarcomas. There are approximately 1000 cases in the United States yearly (3 cases per million yearly). This type of tumor most commonly affects patients between 20 and 50 years old. The most common location for DFSP is around the torso (50%), but is also seen on the legs, arms, neck and head.
Dermatofibrosarcoma Protuberans grows slowly and starts as a flatness or depression in the skin. Commonly is described as a reddish or purplish patch in the skin. Although this tumor is located in the skin DFSP tends to grow deeply into the surrounding fat, muscle and rarely bone.
Histologically it is described as a highly cellular low grader spindle cell tumor with storiform and honeycomb pattern. There are multiple spindled cells with scant cytoplasm and hyperchromatic nuclei in a very symmetric distribution (fig B5 & B6).
Magnetic Resonance Image (MRI) is the most sensitive and specific radiographic study for DFSP. In most instances the MRI appearance is non specific and other types of sarcomas and other conditions can have a similar appearance. This type of tumor demonstrates on MRI low signal on T1-weighted (Fig B1) and equal or similar signal intensity as the adjacent subcutaneous fat on T2-weighted images (Fig A1 & A2). It shows suppression on fat saturation sequences and enhances (Fig A3 & A4) on contrast enhanced sequences.
The mainstay therapy for DFSP is the wide resection of the tumor (Fig B8 – B12). It has a tendency to recur in the same location after it is removed.
Metastases are present in about 5% of cases. In most cases DFSP are low grade tumors and rarely metastasize. Tumors that are large and have been growing for a prolonged period of time can turn high grade and/or dedifferentiate which is associated with a poor prognosis. The most common site for metastases is the lungs however high grade variants may have a strange pattern of metastases.