Overview
Sezary syndrome is a type of lymphoma that affects the skin and other parts of the body. Lymphoma is cancer that happens in the lymphatic system, which is part of the body's germ-fighting immune system.
Sezary syndrome mostly affects the skin, which is why this cancer is considered a type of cutaneous T-cell lymphoma. But Sezary syndrome also affects the blood, which makes it different from other types of lymphoma. Healthcare professionals sometimes say it is a leukemic variant of cutaneous T-cell lymphoma because Sezary syndrome has some features of both lymphoma and leukemia, which is a cancer of the blood and bone marrow.
Some people wonder how Sezary syndrome relates to another condition called mycosis fungoides. Mycosis fungoides happens mostly in the skin, while Sezary syndrome affects the skin, blood and lymph nodes. This suggests that Sezary syndrome and mycosis fungoides are related but distinct conditions. Some people may show features of both conditions at the same time. In some people, mycosis fungoides can progress into Sezary syndrome.
Sezary syndrome can't be cured, but many treatments can help reduce symptoms, improve the skin and slow the growth of the cancer. Treatment often involves skin-directed therapies and systemic treatments that work throughout the whole body. These treatments help manage the disease and improve quality of life.
Sezary syndrome and other T-cell lymphomas are types of non-Hodgkin lymphoma.
Symptoms
Symptoms of Sezary syndrome typically happen fast and affect the whole body. Signs and symptoms may include:
- Severe skin itching, burning or discomfort.
- A scaly rash that causes the skin to look red, purple or gray depending on skin color, a condition known as erythroderma.
- Swollen lymph nodes, which may feel like lumps under the skin. They happen most often in the neck, armpit and groin.
- Thickened skin on the hands and feet.
- Tight or thickened skin around the eyes that causes the eyelid to turn outward. This is known as ectropion.
- Hair loss, including loss of eyebrows or body hair.
- Nail changes, such as thick or brittle nails.
When to see a doctor
Make an appointment with a healthcare professional if you have any symptoms that worry you.
Causes
It's not clear what causes Sezary syndrome. Cancer happens when cells develop changes in their DNA. A cell's DNA holds the instructions that tell the cell what to do. In healthy cells, the DNA gives instructions to grow and multiply at a set rate. The instructions tell the cells to die at a set time. In cancer cells, the DNA changes give different instructions. The changes tell the cancer cells to make many more cells quickly. Cancer cells can keep living when healthy cells would die. This causes too many cells. In Sezary syndrome, the cancer cells can build up in the skin, blood and lymph nodes.
Sezary syndrome gets its name from the type of cells involved. In this cancer, a type of white blood cell called a T lymphocyte transforms into a cell called a Sezary cell. These cells circulate in the blood and build up in the skin.
Risk factors
Factors that may increase the risk of Sezary syndrome include:
- Older age. Sezary syndrome happens most often in older adults
- Mycosis fungoides. In some people, mycosis fungoides can progress into Sezary syndrome.
There are no known ways to prevent Sezary syndrome.
Complications
Sezary syndrome may cause complications such as:
- Frequent infections. People with Sezary syndrome are more likely to get infections because the skin barrier is damaged and the immune system is weakened. These infections can be serious and may include bacterial, viral or fungal infections.
- A switch to a more aggressive form of cancer. In some people, the cancer cells can change into larger and more aggressive cells that grow more quickly and make treatment more difficult. Healthcare professionals sometimes refer to this as a large cell transformation.
- Increased risk of other cancers. People with Sezary syndrome have a higher risk of developing other cancers, including skin cancers and lymphomas.
Feb. 03, 2026