Cutaneous T-Cell Lymphoma (CTCL) is a type of cancer that primarily affects the skin. It arises from a group of white blood cells called T-cells, which are part of the immune system. In CTCL, these T-cells become malignant and can lead to various skin symptoms, including rashes, lesions, and patches that may be itchy or painful. The most common form of CTCL is Mycosis Fungoides, which often starts as red, scaly patches on the skin. Another variant is Sézary Syndrome, characterized by more widespread skin involvement and the presence of cancerous T-cells in the blood. Diagnosis typically involves skin biopsies and other tests to determine the extent of the disease.