Mycosis Fungoides


What is mycosis fungoides?

Mycosis fungoides (my-KOH-sis fun-GOY-deez) is a disease of the T-cell lymphocytes (white blood cells). With this condition, the T-cells become malignant (cancerous) and affect your skin.

Healthcare providers classify mycosis fungoides as a cutaneous T-cell lymphoma (CTCL), a type of non-Hodgkin’s lymphoma that occurs in T-cells in the skin.

What are lymphocytes?

Lymphocytes are a type of white blood cell in the lymph system, part of your immune system. They live in the lymph nodes (small collections of immune cells). They also live in other lymphoid tissue, such as the spleen, skin and bone marrow.

T-cell lymphocytes fight foreign bacteria and activate your immune system. T-cells also help clean up the foreign bacteria after an immune response.

What is the difference between mycosis fungoides and Sézary syndrome?

Mycosis fungoides occurs when T-cell lymphocytes become cancerous. When these cancerous lymphocytes circulate in the blood, they are called Sézary cells.

Sézary syndrome occurs when you have large numbers of T-cell lymphocytes — called Sezary cells — in the blood that can go to the skin and lymph nodes.

Is mycosis fungoides contagious?

Mycosis fungoides is not contagious. You can't pass the condition from person to person.

Who might get mycosis fungoides?

Mycosis fungoides can affect anyone but is most common in adults over 50. Men are twice as likely as women to develop mycosis fungoides.

How common is mycosis fungoides?

Mycosis fungoides is rare. Healthcare providers diagnose around 3,000 people with cutaneous T-cell lymphomas each year. On average, about 70% of all cutaneous T-cell lymphomas are mycosis fungoides.

Because mycosis fungoides progresses slowly, more people may have the condition without yet knowing it.

Symptoms and Causes

What causes mycosis fungoides?

Experts do not know what factors cause mycosis fungoides. Researchers continue to study the effects of environmental factors, such as exposure to certain toxins.

A gene mutation (change) may play a role. Scientists suggest that there may be a link with certain gene types that determine how the body responds to perceived invaders. The condition doesn’t seem to be inherited (passed down through families).

What are the symptoms of mycosis fungoides?

Mycosis fungoides symptoms occur in several phases of skin changes. In the most severe phase, high levels of Sézary cells may cause mycosis fungoides to evolve into Sézary syndrome.

For many people, the first sign of disease is a mycosis fungoides rash. Mycosis fungoides stages include:

  • Premycotic phase: A scaly, symptom-free skin rash. This rash appears in areas of the body not usually exposed to the sun.
  • Patch phase: The skin around the rash becomes thin. It may be itchy and dry, like eczema.
  • Plaque phase: Your skin forms papules (small raised bumps) or lesions (hard bumps).
  • Tumor phase: Tumors form on your skin. They may develop ulcers and get infected.

Diagnosis and Tests

How is mycosis fungoides diagnosed?

Mycosis fungoides shares many symptoms of other skin conditions. It may be challenging to diagnose based on a visual skin exam. Mycosis fungoides is often mistaken for other skin conditions, such as eczema or psoriasis.

To confirm or rule out mycosis fungoides, your healthcare provider will likely use additional tests such as:

How do doctors stage mycosis fungoides?

Your doctor will tell you the stage of mycosis fungoides. Staging is part of diagnosing cancer. Staging groups cancer by its spread and invasiveness.

In general, earlier stages (stages 0-1) mean cancer has just started and not spread very much. Later stages (stages 2-4) indicate that cancer has grown and spread. Knowing the stage helps your healthcare provider determine how to treat the cancer.

Management and Treatment

How is mycosis fungoides treated?

Mycosis fungoides treatment depends on the cancer stage and type of skin changes. Many treatment options focus on relieving symptoms and improving your quality of life.

Your healthcare provider may prescribe:

  • Skin-directed therapy: Topical gels, steroids, retinoids or ultraviolet (UV) light treat cancer on affected areas of your skin. With phototherapy, an oral agent (psoralens) is combined with UV light to destroy cancer cells on your skin. Your provider may also use a topical chemotherapy, such as mechlorethamine.
  • Systemic therapy: Oral drugs such as bexarotene (Targretin®) or methotrexate can treat your whole body. Other classes of drugs include Interferon α and histone deacetylase (HDAC) inhibitors. Intravenous medications include chemotherapy, such as gemcitabine, pegylated liposomal doxorubicin or pralatrexate.
  • Immunotherapy: These drugs boost your immune system to attack cancer cells. Researchers are still learning about how this works.
  • Monoclonal antibody as targeted therapy: These medicines detect and destroy cancer cells. Healthcare providers may use targeted therapy if your body has not responded to other systemic therapy, such as mogamulizumab-kpkc (POTELIGEO®) and brentuximab vedotin.
  • Radiation therapy: With radiation therapy, strong beams of energy from outside your body can destroy cancer cells or stop their growth.

Healthcare providers rarely use traditional chemotherapy for mycosis fungoides. Chemotherapy does not always effectively treat mycosis fungoides. It also carries a significant risk of side effects.

Is there a cure for mycosis fungoides?

There is no known cure for mycosis fungoides. With an early diagnosis, people often live for many years without symptoms.

Care at Cleveland Clinic


How can I reduce my risk of mycosis fungoides?

There is no proven way to prevent mycosis fungoides. You can reduce the risks associated with late-stage mycosis fungoides by scheduling regular appointments with a healthcare provider. Having regular checkups can increase the chances of detecting mycosis fungoides in its early stages.

Perform monthly skin self-checks for rashes, moles or other changes. If you notice any skin changes, schedule an appointment with a dermatologist (skin care doctor).

Outlook / Prognosis

What is the outlook for people with mycosis fungoides?

If you catch mycosis fungoides in its early stages, it is much easier to treat. Many people who receive early diagnosis experience long periods of no symptoms.

More advanced mycosis fungoides may need more invasive treatment. For example, you may need radiation therapy or chemotherapy if cancer has spread to other parts of your body.

Living With

What else should I ask my doctor?

You may ask your healthcare provider:

  • What is the most likely cause of mycosis fungoides?
  • What are my treatment options?
  • Are there any side effects of mycosis fungoides treatment?
  • What is the risk that mycosis fungoides will return after treatment?
  • What happens if I decide not to treat it?
  • How can I lower my chances that mycosis fungoides will return?

A note from Cleveland Clinic

Mycosis fungoides is a type of skin lymphoma. It affects your white blood cells. For many people, the first sign of mycosis fungoides is a skin rash that is otherwise symptom-free. Without treatment, this rash may become itchy or develop ulcers. There is no cure for mycosis fungoides. With timely treatment, many people experience years with no symptoms.

Frequently Asked Questions

Last reviewed by a Cleveland Clinic medical professional on 09/21/2021.

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