Dermatofibrosarcoma protuberans (DFSP)

ALSO KNOWN AS: Bednar tumor, familial dermatofibrosarcoma protuberans, fibrosarcomatous tumors with attenuated dermal surfaces, fibrosarcomatous progression, fibrosarcoma of the skin, metastatic dermatofibrosarcoma protuberans, progressive and recurring dermatofibroma

RELATED CONDITIONS: Dermatofibroma, epidermal inclusion cyst, fibrosarcoma, giant cell fibroblastoma, fibrous histiocytoma, keloid and hypertrophic scar, lymphoma, melanoma, metastatic carcinoma of the skin, morphea

DEFINITION: Dermatofibrosarcoma protuberans (DFSP) is a rare type of skin cancer affecting the inner skin layer (dermis). Derma means that it affects the skin, and protuberans means that it sticks out (protrudes) above the skin.

Risk factors: There is no known cause of DFSP. In a minority of patients, about 10 percent, some type of trauma, such as a burn, scar, or injection site, has occurred at the site where the disease develops. Laboratory studies indicate that a type of chromosome mutation tends to help the previous skin damage evolve into this type of cancer. In this chromosome mutation, material from chromosomes seventeen and twenty-two somehow combine to form another chromosome or switch material from one chromosome to another. However, many people with this chromosome mutation do not develop DFSP, and many who have DFSP do not have this chromosome mutation.

Etiology and the disease process: DFSP is a very slow-growing cancer. It usually starts as a small, hardly noticeable lump on the skin, which may remain for several years. It may get larger and become an irregularly shaped sore or plaque. These can vary in color from red-brown to red-blue or a bit darker than the surrounding skin, and they can bulge out. This lump may be tender or bleed, or it may be painless. This type of cancer most often occurs on the body, arms, or legs. It very rarely appears on the neck or head.

Rarely, DFSP may appear as a thickened or softly depressed area of skin. This type of DFSP may go unnoticed for quite some time until it has grown big enough for a patient to notice and may have spread far underneath the skin. This type of DFSP is difficult to diagnose as it looks very similar to other skin diseases.

DFSP does not generally spread beyond the original tumor site. However, the tumors are very aggressive in moving out underneath healthy skin. The tumor may be much larger under the surface than it appears from the top of the skin. This makes DFSP a difficult cancer to eliminate because the distance the tumor has spread underneath the top layer of skin may make it difficult to remove the entire tumor, and cells that are left behind tend to grow into another tumor. In rare cases, this cancer may spread to lymph nodes or into the bloodstream, where it may spread to the lungs, heart, brain, or bones.

Incidence: This type of cancer is relatively rare, having a rate between .8 to 4.5 new cases per one million people each year, accounting for 18 percent of curatenous soft tissue cancer and 1 to 6 percent of all soft tissue sarcoma. Though it may occur in persons of any race, Black Americans develop this cancer at almost twice the rate of White Americans. An uncommon variant, called Bednar tumor, occurs mainly in Black patients, accounting for around 5 percent of patients. This cancer occurs most often in people between the ages of twenty and fifty. It is rarely found in newborns, children, or adults over eighty.

Symptoms: DFSP appears as a small, red-brown or red-blue tumor on the skin that may develop into a larger, irregularly shaped lump. This lump may feel rubbery or firm. It is attached under the skin so it does not move around when touched. Usually, the lump is not painful. It may develop into a patch of several lumps or nodules.

Screening and diagnosis: There is no screening test or staging system for DFSP. Because the appearance of the skin in a patient with DFSP can be similar to that of a patient with many other conditions, a diagnosis involves a biopsy of the affected skin. This skin is examined under a microscope to determine if cells are growing abnormally. There is no blood test available for determining whether a patient has DFSP. Usually, imaging tests such as computed tomography (CT) or magnetic resonance imaging (MRI) are not used in diagnosis unless the tumors are suspected to have spread into the lymph system or other body areas.

Treatment and therapy: Surgery is generally the first line of treatment for this type of cancer. Usually, the tumor and a large amount of skin around it must be removed to ensure that the entire tumor, growing under the skin where it cannot be seen, is removed. This type of surgery is called wide excision.

Mohs micrographic surgery (MMS) is often used because it allows a surgeon to view the edges of the skin through a microscope during surgery. While removing the tissue around the tumor's edges, the surgeon can keep checking to ensure the skin around the tumor site has no more cancerous cells. Once no more cancerous cells are present in the tissue at the edges of the surgery site, the surgeon can stop removing the skin. This can help ensure the removal of the entire tumor.

When surgery is used to remove DFSP tumors, the surgical site is often large. Depending on the amount of skin removed, a patient may need skin grafts to close the surgery site. The tumors often have ragged edges and unusual shapes, making removal of the entire tumor difficult. As a result, DFSP has a high rate of recurrence. Any cancerous cells left behind tend to grow into another tumor.

If the cancer is large or its removal would cause serious cosmetic damage, such as a scar on the face or in another exposed area, radiation therapy may be used. In radiation therapy, the skin is exposed to high-energy rays that destroy the cancerous cells while doing as little damage as possible to the surrounding healthy tissues. Radiation therapy may also be used as a follow-up to surgery.

Chemotherapy is rarely used with DFSP, as it has proven relatively ineffective. Researchers are developing oral medications and molecular-level therapies to treat this type of cancer. Oral medications may be able to target specific cancerous cells and kill them while causing a few side effects on the rest of the body. Molecular-level therapies use the body’s natural defenses to target and destroy cancerous cells.

Prognosis, prevention, and outcomes: This type of cancer spreads in only one out of twenty patients, but it has a high rate of recurrence. In 20 to 30 percent of DFSP patients, the cancer returns in the same place. Usually, this is because the first occurrence of the cancer was not completely removed. Because of this high recurrence rate, patients must continue to receive follow-up care. Recurrence usually happens within three years, and patients should be seen regularly during that period to assess any tumor sites to ensure that cancerous cells left behind during surgery have not begun to grow.

If the cancer has spread into the lymph nodes or bloodstream, as it does in only about 3 percent of cases, the prognosis is much worse than if the cancer has been contained to tumors in the skin, with death usually occurring within two years. The prognosis is even worse with the variation of this cancer called fibrosarcomatous progression because this variation is a much more aggressive type of cancer. Older patients (over fifty years old) are more likely to have a poorer outcome than younger patients.

Bibliography

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Menon, Gopal, Jennifer Brooks, and Michael L. Ramsey. "Dermatofibrosarcoma Protuberans." National Library of Medicine, 18 Apr. 2024, www.ncbi.nlm.nih.gov/books/NBK513305. Accessed 20 June 2024.

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