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Dermatofibrosarcoma protuberans (DFSP) is a rare form of soft tissue sarcoma that arises just beneath the skin's surface, involving the dermis and potentially the fat or other tissues beneath it. In long-standing cases, DFSP may extend into muscle and fascia, which are tissues that encase and support muscles, organs, and blood vessels. DFSP is most commonly diagnosed on the torso, including the chest, abdomen, pelvis, and back, but can also occur on the arms, legs, head, and neck. It is a relatively uncommon condition, accounting for only about 1 percent of the 13,000 new soft tissue sarcoma cases diagnosed in the U.S. annually, and predominantly affects individuals in their middle age.

Characteristics and Symptoms of DFSP

DFSP is known for its tendency to recur after surgical treatment but is infrequently metastatic. Early signs of DFSP include a firm area beneath the skin that may cause the skin to take on a greyish or red-brown hue. Over time, the condition can develop into several pimple-like bumps, colored red-brown or violet, which can grow to a size of up to 5 centimeters. In some cases, DFSP may also present as a painful, open wound.

Classification of DFSP

Medical professionals categorize DFSP into several types based on cellular composition and other characteristics:

Conventional DFSP is the most common form, with a low risk of spreading after multiple recurrences.

Fibrosarcomatous DFSP (FS-DFSP) exhibits traits of fibrosarcoma and has a higher likelihood of recurrence and spread.

Giant cell fibroblastoma, often affecting children and adolescents, features larger cells.

Myxoid DFSP contains a distinctive tissue known as myxoid stroma.

Pigmented DFSP, or Bednar tumors, contain dark-colored cells and are more prevalent among individuals of Black ethnicity.

Etiology of DFSP

DFSP arises from a genetic alteration involving a translocation between chromosomes 17 and 22. This genetic event is not inherited and is not passed down to offspring. While the exact cause of this mutation in DFSP remains a mystery, some evidence suggests that previous skin injuries, such as scars or tattoos, might be linked to the development of DFSP.

Diagnosis of DFSP

The diagnosis of DFSP typically begins with a physical examination and a needle biopsy to obtain a sample of the tumor for microscopic examination and laboratory tests, including genetic analysis. In certain instances, imaging tests like MRI may be recommended to ascertain the tumor's size and its potential invasion into surrounding tissues, aiding in treatment planning.

Treatment Approaches for DFSP

Treatment at specialized centers like Penn Medicine's Abramson Cancer Center focuses on surgical excision. Mohs surgery is one technique, involving the sequential removal of skin layers and immediate assessment for cancer presence until only cancer-free tissue remains. Alternatively, the tumor may be excised in one piece with a margin of healthy tissue to minimize the risk of recurrence. If the excision margins are not clear, radiation therapy may be advised. In cases where DFSP cannot be surgically removed, or for recurrent or metastatic tumors, targeted therapy with imatinib may be employed to inhibit DFSP's cellular growth pathways.

Post-treatment surveillance is recommended to monitor for potential recurrences, ensuring the best possible outcomes for patients with DFSP.