Cutaneous T-cell lymphoma (CTCL) is a rare type of cancer that begins in white blood cells called T cells (T lymphocytes). These cells normally help your body's germ-fighting immune system. In cutaneous T-cell lymphoma, the T cells develop abnormalities that make them attack the skin.

Cutaneous T-cell lymphoma can cause rash-like skin redness, slightly raised or scaly round patches on the skin, and, sometimes, skin tumors.

Several types of cutaneous T-cell lymphoma exist. The most common type is mycosis fungoides. Sezary syndrome is a less common type that causes skin redness over the entire body. Some types of cutaneous T-cell lymphoma, such as mycosis fungoides, progress slowly and others are more aggressive.

The type of cutaneous T-cell lymphoma you have helps determine which treatments are best for you. Treatments can include skin creams, light therapy, radiation therapy and systemic medications, such as chemotherapy.

Cutaneous T-cell lymphoma is one of several types of lymphoma collectively called non-Hodgkin's lymphoma.