Dermatofibrosarcoma protuberans (DFSP) is a rare type of sarcoma (cancer that develops from bone or soft tissue) that starts in the skin. More specifically, it develops from connective tissue cells in the middle layer of the skin, called the dermis.
The skin is the largest organ in our bodies that protects us from injury, loss of bodily fluids, and helps regulate body temperature. There are three layers of the skin: epidermis (top layer), dermis
(middle layer), and hypodermis (bottom layer). The epidermis is the water-resistant outer layer of the skin that acts as the body's first line of defence. It contains squamous cells (upper layer of epidermis) and melanocytes. The dermis contains the skin's connective tissues, as well as hair follicles, sweat glands, blood vessels, lymph nodes, and nerves. The hypodermis, also known as subcutaneous tissue layer, stores fat (adipose cells), and contains connective tissue, blood vessels, and nerve cells.
As connective tissue is found everywhere in the body, DSFP can develop just about anywhere. However, it is most commonly found in the torso, shoulder, chest, limbs, head and/or neck.
DFSP is slightly more common in males, and tends to develop in people between 20-59 years of age. However, anyone can develop this disease.
Types of DFSP
There are four rare variations of DFSP, which are categorised by the type of cells they develop from.
Pigmented DFSP/Bednar Tumours
Pigmented DFSP, also known as Bednar tumours, is a rare subtype of DFSP that is most commonly found in the shoulder region. It is categorised by the presence of melanin (the substance responsible for pigmentation of the skin, hair, and eyes) within the cancer cells, causing tumour colour to vary. These tumours can be locally aggressive, however they rarely metastasise and often carry a good prognosis.
Myxoid DFSP
Myxoid DFSP is a rare subtype of DFSP that is most commonly found in the arms, legs, and trunk. It is categorised by the presence of myxoid stroma, an unusually blue or purple type of connective tissue), within the cancer cells. These tumours can be locally aggressive, but rarely metastasise and can have a good prognosis.
Giant Cell Fibrosarcoma/Juvenile DFSP
Giant cell fibrosarcoma, also known as juvenile DFSP, is a rare subtype of the disease that is generally found in children and adolescents. It is characterised by abnormally large cancerous cells, and can be aggressive. These tumours rarely metastasise, and can have a good prognosis.
Fibrosarcomatous DFSP
Fibrosarcomatous DFSP, also known as DFSP with fibrosarcomatous differentiation, is a rare subtype of this disease that is most commonly found in the arms, legs, trunk, head, and neck. Its cellular appearance is very similar to ordinary DFSP, but is generally more aggressive. These tumours are more likely to metastasise, and may not have as good as a prognosis as other subtypes of DFSP.
Treatment
When cancers are detected, they are staged and graded based on size, metastasis (whether the cancer has spread to other parts of the body) and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you. However, because of how rare DFSPs are, there is currently no standard staging and grading system for this disease. Instead of staging and grading, your doctor will recommend a treatment plan based on the following factors:
- Cancer location.
- Whether or not the cancer has metastasised.
- Your age.
- General health.
- Your treatment preferences.
Your doctor may also recommend genetic testing, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.
Treatment options for DFSP may include:
- Surgery, potentially including:
- Surgical excision (minor surgical procedure to remove the cancer).
- Mohs micrographic surgery (specialised surgery that removes thin layers of cancer in stages until completely removed).
- Reconstructive surgeries – such as a skin flap or skin graft (suitable for patients who have had a large skin cancer removed).
- Radiation therapy.
- Targeted therapy, potentially including tyrosine kinase inhibitors such as Imatinib.
- Clinical trials.
- Palliative care.
For more information on the treatment options, please refer to the Rare Cancers Australia treatment options page.
Risk factors
Because of how rare DFSP is, there has been limited research done into the risk factors of this disease. However, studies have shown a potential link between previous skin injury and the development of DFSP.
Early symptoms
Early symptoms of DFSP may include:
- Painless plaque (thickened area of skin) or nodule on skin.
- Rubbery or firm nodule on skin.
- Red-brown, pink, or blueish discolouration of nodule.
- Soft, depressed (or indented) area of skin (rare).
- Ulceration of nodule over time.
Not everyone with the symptoms above will have cancer but see your general practitioner (GP) if you are concerned.
Diagnosis/diagnosing
If your doctor suspects you have a DFSP, they will perform diagnostic tests to confirm the diagnosis, and refer you to a specialist for treatment.
Physical Examination
Your doctor will collect your overall medical history, as well as your current symptoms. Following this, they may examine your body to check for any abnormalities.
Imaging & Blood Tests
The doctor will take images of your body using magnetic resonance imaging (MRI), a computed tomography scan (CT scan), x-ray and/or ultrasound, depending on where it is suspected the cancer is. The doctor may also look at other parts of the body and looks for signs of metastasis. Additionally, a blood test may be taken to assess your overall health and help guide treatment decisions.
Biopsy
Once the location of the cancer has been identified, the doctor will perform a biopsy to remove a section of tissue using a needle. This can be done by either a fine needle aspiration (FNA), a core needle biopsy (CNB), or an incisional biopsy. Once a sample has been removed, it will be sent to a lab and analysed for cancer cells.
Prognosis (Certain factors affect the prognosis and treatment options)
While it is not possible to predict the exact course of the disease, your doctor may be able to give you a general idea based on stage, rate/depth of tumour growth, susceptibility to treatment, age, overall fitness, and medical history. Generally, early stage DFSP has a good prognosis and survival rates. However, if the tumour has become advanced and has spread, the prognosis may not be as good. It is very important to discuss your individual circumstances with your doctor to better understand your prognosis.
References
Some references are to overseas websites. There may be references to drugs and clinical trials that are not available here in Australia.