Sézary Syndrome is a rare type of blood cancer that affects the skin and is classified as a form of cutaneous T-cell lymphoma. It is characterized by the presence of cancerous T-cells in the bloodstream, leading to symptoms such as red, itchy skin, and swollen lymph nodes. Patients may also experience hair loss and thickened skin. The condition is named after the French dermatologist Albert Sézary, who first described it in the 1930s. Diagnosis typically involves blood tests, skin biopsies, and imaging studies. Treatment options may include chemotherapy, phototherapy, and targeted therapies to manage symptoms and control the disease.