Skin lymphoma (also known as cutaneous lymphoma) is a rare form of skin cancer that is not linked to sun exposure. There are several types of skin lymphoma and, as a category, they are rare, affecting about 6 in 1 million people. Yale Medicine is an internationally recognized center of expertise in diagnosing and treating skin lymphomas that range from early-stage to complex disease.

Skin lymphoma is a group of rare, usually slow-growing skin cancers that start in lymphocytes, which are a kind of white blood cell. While most lymphocytes are in lymph nodes, a key part of the body’s immune system, they are also present in the skin. When skin lymphocyte cells become damaged and grow uncontrollably, cancer can develop. Skin lymphomas typically present as a visible rash or as growths on the skin.

Broadly, there are two types of skin lymphomas: B-cell lymphomas and T-cell lymphomas (B cells and T cells are subtypes of lymphocytes). B-cell and T-cell skin lymphomas behave differently.

Doctors don’t know what causes skin lymphomas. They aren’t associated with any viruses, nor is there a genetic link. But there are some recognized risk factors, including:

• Age: Generally, skin lymphomas appear in older adults. But they also affect middle-age and younger people, including children.
• Race: There is a higher incidence among African-Americans of the most common type of T-cell skin lymphoma: mycosis fungoides.
• Sex: Most types of skin lymphoma are more likely to strike men than women.
• Damaged immune system:  People with weakened immune systems, or who are receiving treatments that weaken it, are at higher risk.

The symptoms of a skin lymphoma depend on whether it’s a T-cell or B-cell lymphoma.

Patients with T-cell lymphomas generally have flat rashes called patches or plaques. The rash may start in a small area and then extend over large areas of the body. The patches may be red, itchy and dry, and cracks may form in the skin. 

Other symptoms include fatigue, elevated white blood cell count and enlarged lymph nodes. In severe cases, T-cell lymphomas may cause disfiguring tumors to grow out of the skin.

B-cell lymphomas typically show up on the skin as raised, solid, nodular lesions, usually pimple-sized or larger.

Diagnosing skin lymphoma can be tricky because it’s easily confused with other, noncancerous, dermatologic conditions that cause similar symptoms. Diagnosis is also difficult because skin lymphomas usually grow slowly. 

“Typically, a patient may have something on his or her skin for several years before it’s properly diagnosed,” says Lynn Wilson, MD, MPH, clinical director of Therapeutic Radiology at Yale Medicine. “They may think it’s a bug bite, or they may think it’s an irritation or an allergic reaction, and it doesn’t really bother them that much.”

 Often, Dr. Wilson says, it’s not until standard skin treatments fail that lymphoma is suspected.

To obtain a proper diagnosis, you're likely to be seen first by a dermatologist, who examines the skin. Next, the dermatologist performs a skin biopsy, a simple procedure done in the office in which a sample of skin tissue is removed. The biopsy is then analyzed by a pathologist, a specialist who determines whether cells from the sample are malignant, and what kind of cells they are.

Because skin lymphomas are rare, they can be particularly hard to diagnose and classify. Biopsies may be sent to a major medical center that has specific and extensive expertise in diagnosing the condition. Yale Medicine is one such center. “We have dermatopathologists who are pathologists specializing in skin pathology,” Dr. Wilson says. “And they’re very subspecialized. They are very good at determining what is skin lymphoma and what isn’t.”

A team approach is used to treat skin lymphomas. Dermatologists, medical oncologists,  radiation oncologists and surgeons may all be involved in treating a patient. Treatment options depend on how advanced the cancer is and such factors as the patient’s overall health and responsiveness to different treatment methods. The methods we use to treat skin lymphoma include:

Radiation therapy: Radiation therapy is a common treatment for skin lymphoma. It consists of a machine aiming radiation beams at specific parts of the body. The radiation disrupts the functioning of cancer cells so that they cannot reproduce. Those therapies are administered by a radiation oncologist who specializes in treating cancer with radiation. Each treatment session lasts about 20 minutes and is performed four to five days a week for three to nine weeks, depending on the clinical situation.

At Yale Medicine, we use two kinds of radiation treatment to treat skin lymphomas: Total skin electron beam therapy (TSEB) or ;ocalized radiation

With total skin electron beam therapy, the entire surface of the skin receives radiation. The radiation is delivered as the patient stands on a platform in different positions so that the entire surface area of the skin is “hit” with radiation. The electron beam doesn’t penetrate deep into the body, so effectively only the skin is treated and internal organs are not affected.

TSEB is “very complicated technically,” Dr. Wilson says. “It’s advantageous for patients that this be done in a center with experience.” Yale Medicine is one of very few medical centers that has vast experience treating people with TSEB. Patients from across the United States and abroad travel to Yale Medicine to take advantage of our doctors’ expertise.

As opposed to the entire skin area, localized radiation targets a small section of skin, including just single lesions.

There are several possible side effects of radiation therapy. Whether or not you experience just a few or several of them depends on the treatment dose used, the extent of the radiation fields and your response. 

Most of the side effects are related to the skin. The skin may become red or swollen, or blisters may form. In addition, the fingernails and toenails may become weak or break easily. 

Other possible side effects include hair loss, cataracts and fatigue. Most patients recover from those side effects within several weeks after treatment, although hair can take longer to grow back.

Topical treatment: Topical treatments are prescribed by a dermatologist and are applied to the skin. This includes such medicines as steroid creams, which are put directly on the lesions. Topical treatment is most effective in early skin lymphomas where the lesions cover a small area and the cancer has not spread to other organs.

UV light therapy: Dermatologists also may use ultraviolet light therapy, in which UV radiation is aimed at the skin using special lamps. (UV radiation is a less intense form of radiation than that used in radiation therapy.) The UV light kills cancer cells in the skin; this therapy is most effective on thinner skin lesions.

Systemic treatment: If the lymphoma has spread beyond the skin, treatments are likely to focus on the whole body. Systemic treatments consist of medicines that enter the bloodstream and are then delivered throughout the entire body. Dermatologists or medical oncologists, for example, may prescribe a pill with similar medicinal qualities as a topical cream and may prescribe injections. Another systemic treatment dermatologists perform is photopheresis, a blood treatment in which blood is drawn from the patient and treated with ultraviolet light and then reinfused back into the patient.

Medical oncologists also provide systemic treatments, ranging from oral drugs to chemotherapy, in which powerful drugs are administered that kill cancer cells throughout the body.

Surgery: Surgery to treat skin lymphomas is largely reserved for early-stage B-cell lymphomas that are isolated and only in one location. “If you have a little pimple-type lesion,” Dr. Wilson says, “or something that's only a centimeter-wide on your skin, then that can typically be surgically excised with very good results.” Surgery is typically not used for T-cell lymphomas because those types are usually spread over at least several centimeters of skin, and thus would require extensive surgery. In those cases radiation is preferred.

Yale Medicine has been an international center of expertise in skin lymphomas for several decades. The team at Yale Medicine is skilled at treating difficult advanced cases of lymphoma and early-stage cases.

Each patient is treated by a multidisciplinary team that collaborates to devise the most effective treatment plan. “We're very thoughtful about thinking of the patient as a whole person,” Dr. Wilson says, “and considering logistically what's easiest for them and their families.”