Dermatofibrosarcoma Protuberans

Dermatofibrosarcoma protuberans (DFSP) is a rare type of skin cancer that starts in muscle, fat and in your skin’s middle layer (the dermis). These tumors can also affect bones. This cancer grows slowly and rarely spreads. But it can return after surgical treatment. It may start in areas that have skin damage from burns, scars or tattoos. DFSP is a rare cancer that affects approximately 4 out of 1 million people worldwide each year. 

Types & Stages

The types of dermatofibrosarcoma protuberans include:

• Bednar tumors (pigmented DFSP). They contain cells that have a lot of melanin, the substance that gives skin its color. Bednar tumors may have a mix of colors, including red, brown, blue and purple. These tumors account for about 5 percent of DFSP diagnoses.
   
• Giant cell fibroblastoma. It consists of giant cells. This type is also known as juvenile DFSP because it mostly affects children and teens.
   
• Fibrosarcomatous dermatofibrosarcoma protuberans (DFSP-FS). This is a more aggressive cancerous soft tissue sarcoma.
   
• Myxoid DFSPs. These are made of an abnormal type of connective tissue called myxoid stroma. This type of DFSP is rare.

Signs & Symptoms

Early symptoms of dermatofibrosarcoma protuberans (DFSP) are easy to dismiss or not notice. The tumors typically appear on your chest, back, shoulders, abdomen or buttocks. Tumors can also form on your arms, legs, scalp and inside of your mouth. 

• At first, you may notice a small patch of skin that looks like a bruise. The spot is flat and painless. It may feel rough and look discolored.
   
• In infants and children, DFSP can look like a birthmark. These spots are usually about 1/2 inch to 2 inches (1 centimeter to 5 centimeters) across.
   
• DFSP symptoms become more noticeable as the cancer grows. The growing tumor pushes into the top layer of skin. Firm lumps (nodules) of tissue appear on the skin (“protuberans”). You may notice that the nodules are:
  • easy to crack open or bleed
  • firmly attached to your skin (doesn’t move)
  • getting bigger and stretching your skin
  • hard or rubbery
  • reddish-brown to violet, blue or red
  • tender

A noncancerous skin condition called cellular dermatofibroma can look like DFSP, especially during the cancer’s early stage. Cellular dermatofibromas are benign soft tissue tumors that typically appear on your legs. They may be itchy or painful. Most dermatofibromas don’t need treatment.

Diagnosis

If you’re first seen by your primary care doctor and skin cancer is suspected, you may be referred to a dermatologist, a doctor who specializes in skin diseases. This doctor will look at the area more closely and may perform a skin biopsy. 

• Skin biopsy. This is a procedure to remove cells from the surface of the body so that they can be tested in a lab. The tests can show whether cancer cells are present in the skin. Biopsy types include: 
   
  • Punch biopsy. For this, a tool that looks like a tiny round cookie cutter is used to remove a deeper sample of skin. Your doctor rotates the punch biopsy tool on the skin until it cuts through all the layers of the skin. The sample is then removed, and the edges of the biopsy site are stitched together.
     
  • Incisional biopsies. A surgical knife is used to make an elliptical or circular cut through the full thickness of skin. A wedge or sliver of skin is removed, and the edges of the cut are stitched together. An incisional biopsy removes only part of the tumor. 

Pathologists examine the tissue under a microscope to check for cancer cells. If the skin biopsy determines you have DFSP, you may get an MRI to determine the size and depth of the tumor.

Treatment

Surgical removal is the treatment of choice for DFSP. 

• Mohs surgery. Also known as Mohs micrographic surgery or MMS it is used to remove DFSP tumors. In this procedure, the skin (including the tumor) is removed in very thin layers. Each layer is quickly frozen and looked at with a microscope. If cancer cells are seen, the doctor removes another layer of skin. This is repeated until a layer shows no signs of cancer. This is a slow process, often taking several hours, but it means that more normal skin near the tumor can be saved, which can help the area look better after surgery.
   
• Wider surgical excision. Dermatofibrosarcoma protuberans tends to grow in an irregular shape. This makes the cancer hard to remove completely. If Mohs surgery isn’t available, your doctor may recommend wider surgical excision to remove the cancer cells and some of the healthy tissue around it, called the margins. This makes it more likely that all the cancer cells are removed.

DFSP tumors can grow back after surgical removal. About 20 to 30 percent or more of people experience a recurrence within three years after wide excision, and up to 4 to 5 percent recur after Mohs surgery. 

• Radiation treatment. Can be done for incompletely excised DFSP or inoperable DFSP tumors.
   
• Targeted therapy. Targeted therapy medicines attack specific chemicals present in cancer cells. Blocking these chemicals with targeted therapy medicines cause cancer cells to die. Your doctor may recommend this treatment if surgery is not an option or if your cancer returns after surgery.

Causes & Risk Factors

Risk factors for dermatofibrosarcoma protuberans include:

• Age. This cancer can happen at any age, but it happens most often in adults ages 20 to 50.
   
• Race. This cancer happens more often in Black people than it does in people of other races.
   
• Prior skin injury. People with skin that has been burned, treated with radiation, scarred from surgery, and in some cases tattooed, may be more likely to have this cancer.
   
• History of dermatofibrosarcoma protuberans. This cancer can come back locally after surgical removal.
      

Screening

With skin self-exams and skin checks by a health care professional like a dermatologist, dermatofibrosarcoma protuberans can often be found early. When skin cancers are found early, they are likely to be easier to treat.