Dermatofibrosarcoma Protuberans

What is Dermatofibrosarcoma Protuberans?

Dermatofibrosarcoma protuberans, or DFSP, is a rare type of skin cancer usually found on the torso and upper limbs. It typically emerges as a slow-growing, firm, and dark red or blue patch. Because DFSP grows slowly, it can sometimes take months to years before it is detected. Most instances of DFSP are connected with a particular genetic shift which generates a specific protein called COL1A1-PDGFB.

DFSP is known for penetrating significantly into surrounding tissue, often far beyond the spot that’s visible. However, it rarely spreads to other parts of the body unless it morphs into another type of cancer called fibrosarcoma. The usual treatment involves surgery to remove the cancer along with some of the surrounding tissue. This can be achieved through specialized surgical techniques like Mohs surgery. For cases where it’s hard to get a clear zone around the cancer, radiation therapy can be used to lessen the chances of it coming back. More recently, drugs targeting specific enzymes – called tyrosine kinase inhibitors – have demonstrated encouraging results in treating advanced or spread-out cases. After treatment, patients need regular check-ups to monitor for any signs of the cancer’s return.

What Causes Dermatofibrosarcoma Protuberans?

Ninety percent of patients with a type of skin cancer known as DFSP, as well as those who develop a variant of it called DFSP-FS, usually show a specific change in their genes, or a translocation. This involves a swap between two specific regions of DNA on chromosomes 17 and 22.

But in some patients, this typical translocation isn’t present. Instead, these patients might show a different translocation involving a gene known as PDGFB on chromosome 22. In certain cases, the transformation from standard DFSP to the DFSP-FS variant is related to an increase in the activity of the PDGFB/COL1A1 fusion gene, although this doesn’t happen all the time.

Moreover, scientists have observed something known as microsatellite instability in some cases. This is characterized by changes in the number of times certain small sequences of DNA are repeated compared to what is typically inherited. After these changes, commonly the cancer acquires mutations in a protein called TP53, especially in instances where the cancer features characteristics of a highly aggressive type of cancer called high-grade sarcoma.

Risk Factors and Frequency for Dermatofibrosarcoma Protuberans

DFSP, or Dermatofibrosarcoma protuberans, is a rare kind of tumor. It occurs in 0.8 to 4.5 cases per million people each year. Despite its rarity, it accounts for a small portion of all soft tissue and skin tumors. Both males and females are equally prone to developing DFSP. Although it’s most commonly diagnosed in adults aged between their 30s and 50s, it can occur at any age. It’s worth noting that around 6% of DFSP cases occur in children and its growth can speed up during pregnancy.

• DFSP is a rare tumor, occurring in 0.8 to 4.5 out of a million people per year.
• It accounts for 1-6% of all soft tissue tumors and 18% of skin tumors.
• Both men and women are equally likely to develop DFSP.
• It is most common in adults aged between their 30s and 50s, but can occur at any age.
• About 6% of DFSP cases are in children.
• The tumor might grow faster during pregnancy.
• There are different types of DFSP, with DFSP-FS accounting for 5-15% of cases and the Bednar or pigmented variant being less than 5% of cases.
• DFSP, including the pigmented variant, is more common in Black people than White people.

Signs and Symptoms of Dermatofibrosarcoma Protuberans

Dermatofibrosarcoma Protuberans (DFSP) usually appears as a firm, skin-colored to red-brown skin patch, which gradually grows into raised bumps of a purple to red-brown color. Over time, these usually painless lesions can look similar to scar tissue or keloids, which may lead to mistaken diagnosis, especially in the early stages. The tumor typically has slow growth over a period of months to years and can grow a few centimeters wide. It is generally attached to the outer skin layer but can move relative to the structures beneath the skin. In time, the tumor might become attached to these underlying structures. Occasionally, DFSP can develop from preexisting scars or tattoos. As the lesions grow, they may open up (ulcerate) and cause pain.

About half of these lesions are located on the body’s trunk, while 35% present on the limbs, and 15% on the head and neck.

Testing for Dermatofibrosarcoma Protuberans

If a person has a slowly developing skin lump, doctors might think it could be dermatofibrosarcoma protuberans (DFSP). The initial examination tool is a dermoscopy – a special test that can hint at DFSP, but can’t prove it for sure. A definite diagnosis can only be made through a biopsy using a core needle or by removing the entire lump. A full medical history, physical examination, including checking lymph nodes and a complete skin examination, is vital. Those with a history of treatment for similar conditions may need a fine needle aspiration test.

Typically, doctors can diagnose DFSP by looking at the biopsy sample under a microscope after staining it with a special dye – a process known as light microscopy. Sometimes, it might be challenging to tell DFSP apart from other skin growths like dermatofibroma, fibrosarcoma, leiomyosarcoma, undifferentiated soft tissue sarcoma, or atypical fibroxanthoma. So, for any suspected cases of DFSP, the biopsy sample is also tested using a method called immunohistochemistry. This method looks for certain proteins in the sample that indicate DFSP. Around 80% to 100% of DFSP cases show positive results for the protein CD34.

In cases where the diagnosis is still unsure, molecular testing, like the reverse transcription polymerase chain reaction (RT-PCR) or fluorescence in situ hybridization (FISH), might be used. These tests check for a particular genetic mutation linked to DFSP. Both tests are specific, but the FISH test is more sensitive than RTPCR and can pick up the mutation in 90% of cases compared to 72%.

DFSP usually affects only the superficial layer of the skin, so doctors can determine how far the tumor and lymph nodes are involved through a physical examination. Imaging tests are generally not part of the standard diagnosis process. They may only be used for large or recurring tumors if the doctor suspects that the tumor has invaded bone or needs to understand how far the disease has spread. If imaging is needed, magnetic resonance imaging is the preferred method. Computed tomography (CT) scan would only be useful if bone involvement or lung metastasis is suspected. Since it is very uncommon for DFSP to spread through the body, extensive testing usually isn’t necessary. Some professionals suggest having a lung x-ray or CT before treatment, but there are no specific recommendations about this.

Treatment Options for Dermatofibrosarcoma Protuberans

The first step in treating localized DFSP (a type of cancer affecting the deep skin layers) is surgically removing the tumor, aiming for no cancer cells at the edges of the removed tissue. The size and location of the tumor generally dictate the most suitable surgical procedure. Usually, surgeons don’t remove nearby lymph nodes because this cancer has a low chance of spreading to these parts of the body.

Planning the surgical removal is challenging due to the delay in diagnosis and the tumor’s ability to spread into nearby tissues. It’s important to note that almost half of the patients may see their cancer return if treated with simple excision. This is due to most recurrent tumors being more aggressive – they’re likely to invade muscle, bone or cause the cancer to spread far from the original site. For these reasons, having a safe margin of healthy tissue around the removed tumor is crucial.

There are a few different surgical techniques used. Wide Local Excision (WLE) is one method. It’s important to note in WLE that the risk of the cancer returning depends on the size of the healthy tissue margin. For example, one study demonstrated that the cancer returned in 47% of patients who had less than 3 cm margin around their tumor compared to only 7% in patients with 3 to 5 cm margins. Aiming for clear margins of 2 to 4 cm around the tumor, where possible, is often recommended by the NCCN.

Mohs Micrographic Surgery (MMS) is another technique. This process involves progressively removing thin slices of tissue and examining them under the microscope during surgery to ensure all cancer has been removed, reducing the chance of the cancer returning. Some studies suggest that MMS could result in fewer recurrences than WLE, with a 1% recurrence rate in MMS versus a 7.3% rate in WLE. Although this approach may be beneficial, we need more trials and long-term data to confirm this. One significant advantage of MMS is that it requires smaller healthy tissue margins, which results in smaller wounds and less complicated recovery.

Radiation Therapy may also be used but is rarely the sole treatment. It might be used after surgery if the margins are not clear or the closest margin is less than 1 cm and MMS wasn’t performed, or when it’s not possible to surgically remove recurrent or metastatic disease. Radiation doses range from 50 to 70 Gy and typically go 3 to 5 cm beyond the surgical margins when possible.

A type of medication called Imatinib, which works by inhibiting specific molecular targets in the cancer cells, might be used for DFSP that can’t be removed surgically, has returned after initial treatment, or has spread to other parts of the body. This medication may cause some side effects like upset stomach, swelling, fatigue, anemia, and rash. Most individuals respond well to it, with 65% showing positive reactions. Further research is needed to figure out if and how this medication might be incorporated with surgery in treating localized cases of DFSP.

Lastly, after treatment, patients should regularly self-examine and have their primary site checked every 6 months for 3 to 5 years, followed by lifelong annual exams. Imaging tests, blood counts, and liver function tests are only needed if symptoms suggest they might be necessary. It’s important to note that cancer spread is more likely to occur in patients with recurrent DFSP or a variant known as DFSP-FS, so these patients might require more routine imaging follow-ups.

What else can Dermatofibrosarcoma Protuberans be?

When doctors are trying to diagnose Dermatofibrosarcoma Protuberans (or DFSP for short), they have to keep in mind other possible conditions that may look similar. These can include:

• Fibrous Histiocytoma, which is a tumor composed of modified cells of skin and connective tissues.
• Solitary Fibrous Tumor, a rare type of tumor usually found in the pleura, the thin layer of tissue that covers the lungs, but can occur anywhere in the body.
• Spindle Cell Lipoma, which is a slow-growing fatty lump mostly located in the back of the neck or shoulders.
• Angiosarcoma, a cancer that forms in the lining of blood vessels and lymph vessels.
• Peripheral Nerve Sheath Tumors, tumors that form in the protective lining of the nerves that extend from the spine into the body.
• Spindle Cell Melanoma, a type of skin cancer.
• Angiomyxoma, a rare and usually benign soft tissue tumor.
• Myxoid Sarcoma, a rare form of soft tissue cancer.
• Synovial Sarcoma, a rare type of cancer that can occur in various locations in the body.
• Sarcomatoid Carcinoma, a type of aggressive cancer that can begin anywhere in the body.
• Cutaneous Melanoma, a skin cancer that develops when melanocytes (the cells that produce the pigment melanin) start to multiply uncontrollably.
• Dermatofibroma, a common benign skin nodule.
• Dermatologic Metastatic Carcinoma, a carcinoma that has spread (metastasized) to the skin from a primary tumor elsewhere in the body.
• Epidermal Inclusion Cyst, a type of cyst that forms from the cells in the top layer of skin (epidermis).
• Keloid, a type of raised scar.
• Morphea, a skin condition that causes patches of skin to become hard or thick.

To identify DFSP accurately among these, doctors would need to thoroughly examine the patient and carry out the necessary tests.

What to expect with Dermatofibrosarcoma Protuberans

The outlook for individuals with DFSP (Dermatofibrosarcoma Protuberans) is commonly positive, as shown by a 10-year survival rate of 99.1%. However, those with the condition that has spread to other parts of the body, often live for approximately two years after diagnosis. The overall likelihood of the disease spreading is 5%, which includes a 1% chance of spreading to nearby lymph nodes and a 4% chance of spreading to distant areas of the body.

Although spreading of the disease is not common, recurrence in the original location is a more common issue that can affect the patient’s quality of life. Factors that increase the risk of worse outcomes include being older than 50, having a variation of the condition known as DFSP-FS, a high rate of cell division (mitotic index), and a high cell concentration. Proper treatment, including a more extensive surgical removal, can improve the overall outlook of the disease.

Possible Complications When Diagnosed with Dermatofibrosarcoma Protuberans

What difficulties can you face after DFSP treatment? Most issues arise from the size of the surgical wound and chances of the disease returning locally. You might experience wound-related problems such as infections. Covering the surgical wound might be difficult and you might need a skin graft or intricate plastic surgery. You could also have skin contractions, and abnormal growth of scar tissue. These complications can be reduced by utilizing Mohs micrographic surgery (MMS). Death is rare, but it can happen if the disease spreads to other parts of the body.

Common Complications:

• Wound-related infections
• Difficulties in covering the surgical wound
• Possibility of needing a skin graft or complex plastic surgery
• Skin contractions
• Abnormal growth of scar tissue
• Risk of death if the disease spreads to other parts of the body

Preventing Dermatofibrosarcoma Protuberans

DFSP, or Dermatofibrosarcoma Protuberans, is a rare skin cancer. Although it usually doesn’t spread to other parts of the body, it can grow and damage nearby tissues. Regular skin check-ups and seeking medical help for any unusual skin marks or lumps can help spot the disease early, leading to better results from treatment. Patients should also understand how DFSP typically looks – it often starts as a small, unnoticed bump or patch on the skin that slowly grows over a long period, sometimes months to years. Because the growth is so slow, it’s usually not diagnosed for quite some time, which is why it’s crucial to report any changes in skin marks to doctors immediately.

When it comes to treating DFSP, surgery to remove the tumor is generally the preferred method. However, patients should be aware that the surgery might leave a noticeable scar. They should also understand that although the chance of the cancer spreading to other parts of the body is low, there is a high possibility of the tumor coming back in the same area, even after surgery. Therefore, it’s important to keep all follow-up appointments with healthcare providers to keep a close watch on the area and deal with the return of the tumor promptly if it does happen.

By learning about DFSP and taking charge of their skin health, patients can help in the early detection and treatment of the disease. Enhanced awareness, consistent check-ups, and active involvement in their health can make a big impact on the outcomes of this rare skin cancer.