context: Sometimes a red rash is more than an annoying skin problem. It can be a sign of illness, including a blood cancer with a big name: mycosis fungoides. This condition, also known as Alibert- Bazin syndrome, is rare. It happens when white blood cells called T-cells grow out of control and move from the blood into the skin. This causes the rash, which can be itchy. When cancerous T-cells are found in your blood as well as in your skin, it's called SÃ©zary syndrome. It's not clear if SÃ©zary syndrome is an advanced form of mycosis fungoides or something different. Doctors don't know what causes mycosis fungoides. It could be related to a virus, exposure to a chemical, or your genes. It can happen at any age, but most people get it in their 50s or 60s. Men are two times more likely than women to have it. Mycosis fungoides usually develops slowly and moves through four phases. But not everyone goes through all of them: First phase: a scaly red rash, usually in areas that don't get sunlight such as your rear end. There are no other symptoms in this phase, and it may last months or even years. Second phase:a thin red rash that looks like patches. Third phase:small raised bumps or hard plaques that may be red. Fourth phase: tumors or bumps that may look like mushrooms. They can break open and get infected. You can have patches, plaques, and tumors at the same time. But most people who've had mycosis fungoides for many years only have the first two. It usually doesn't go beyond the skin. Many people live a normal life while treating the rash. However, in 10% of people, the cancer spreads to lymph nodes or other organs, which can be serious. Some people also develop SÃ©zary syndrome. The cancerous cells are found in your blood, and almost all your skin is affected. It may look like you have sunburn, and your skin may itch like crazy. SÃ©zary syndrome grows and spreads fast and is more difficult to treat than mycosis fungoides. It can be hard for your doctor to know for sure that you have mycosis fungoides. The patches or plaques can look like eczema, psoriasis, or another common skin problem. It's possible to have it for years before you get the right diagnosis. Your doctor will take a small sample of your skin -- a biopsy -- and put it under a microscope to look for signs of the cancer. You might need several biopsies to confirm it. Mycosis fungoides is rarely cured, but some people stay in remission for a long time. In early stages, it's often treated with medicines or therapies that target just your skin. Your doctor may use more than one approach: Creams, gels, or lotions: These include corticosteroids, vitamin A medicines called retinoids, and chemotherapy drugs that are spread on the skin. They can clear the rash, control the cancer, and get rid of the itch. Phototherapy: This uses ultraviolet light rays to heal the skin. Sometimes, you take a drug beforehand that makes T-cells more sensitive to the light. Radiation: Electron beam radiation works well against mycosis fungoides. It uses very tiny electrically charged particles (electrons) to target and kill cancer cells. This type of radiation only enters the upper layers of your skin, so deeper tissues and organs are safe. It's given in two ways: Total skin radiation: Your whole body may need it if you have mycosis fungoides spots in lots of places. Spot treatment: If you only have a few trouble spots, radiation can target just those areas. This is often used when other therapies haven't worked. If your cancer is more advanced, your doctor may suggest whole body therapies. These include: Chemotherapy: Strong drugs target cancer and other cells that divide quickly. Targeted and biologic therapy: Some drugs identify and attack specific parts of cancer cells. Others boost your immune system to fight them. Retinoid pills: These change the way cancer cells grow and mature. Photopheresis: This therapy uses ultraviolent light to treat cancerous cells in your blood. It's like giving blood, but instead of it going into a collection bag, blood goes into a special machine that takes out T-cells. They're treated with a drug and then exposed to the UV rays. The cells are mixed back in with the rest of your blood and returned to your body. This usually is used to treat advanced cases of mycosis fungoides and SÃ©zary syndrome. Doctors think it works by killing some cancer cells and by boosting your body's immune attack against other ones. This cancer can make your skin very dry and itchy. Here are a few things you can do: Take short, lukewarm baths or showers. Long, hot ones can make dryness and itchiness worse. Pat your skin dry -- don't rub it. Use an unscented skin moisturizer after bathing so moisture gets locked in. Put a cold compress on areas that are really itchy. The Cutaneous Lymphoma Foundation has an online community that can offer more tips and support.