Mycosis fungoides (MF)

Mycosis fungoides (MF) is the most common subtype of cutaneous T-cell lymphoma (CTCL). It is an indolent (slow growing) non-Hodgkin lymphoma (NHL) that develops over many years or even decades. It accounts for around half of all skin lymphomas.

On this page:

Cutaneous T-cell lymphoma – early stage fact sheet PDF

Cutaneous T-cell lymphoma – late stage fact sheet PDF

Overview of mycosis fungoides (MF)

Mycosis fungoides (MF) is the most common subtype of cutaneous T-cell lymphoma (CTCL). It is an indolent (slow growing) non-Hodgkin lymphoma (NHL) that develops over many years or even decades.  It accounts for around half of all skin lymphomas.

Mycosis fungoides (MF) starts in the skin and tends to remain only in the skin.  MF can appear as patches, plaques or tumours. MF often occurs in areas of the skin that are protected from the sun by clothing.

Types of mycosis fungoides (MF)

There are four main types of mycosis fungoides (MF), that include:

  • Classic mycosis fungoides
  • Folliculotropic mycosis fungoides
  • Pagetoid reticulosis (Woringer-Kolopp disease)
  • Granulomatous slack skin (GSS)

Who is affected by mycosis fungoides (MF)?

Mycosis fungoides (MF) most commonly affects older adults.  MF is slightly more common in men than women.

Symptoms of mycosis fungoides (MF)

The symptoms of mycosis fungoides (MF) can include:

  • Painless swelling or lump, mainly in the neck, groin or armpit
  • Irregularly shaped, oval or ring-like, dry or scaly patches most common on chest, back and buttocks.
  • Sometimes slightly thicker and raised areas of skin develop (plaques)
  • Raised lumps on skin that can ulcerate.
  • In very few people the skin becomes red, thickened and sore (erythroderma)

Diagnosis and staging of mycosis fungoides (MF)

A skin biopsy is always required for the diagnosis of MF. A biopsy is an operation to remove a lymph node or other abnormal tissue to look at it under the microscope by a pathologist to see what the cells look like. The biopsy can be done under local or general anaesthetic depending on what part of the body is being biopsied.  

Several skin biopsies (also called a punch biopsy) may be needed before the doctor is able to confirm the diagnosis. 

Waiting for results can be a difficult time and it may help to talk to family, friends or a specialist nurse.  

Staging of mycosis fungoides (MF)

Once a diagnosis of follicular lymphoma (FL) is made, further tests are required to see where else in the body the lymphoma is spread and how much of the body is affected.  This is called staging.  

There are four stages from stage 1 (lymphoma in one area) through to stage 4 (lymphoma that is widespread). 

To find out the stage of lymphoma, the doctor checks:

  • How the skin is affected-plaques, patches or tumours
  • How widespread the MF is on the skin  
  • Whether the lymphoma is in the lymph nodes
  • Whether the lymphoma is in any organs

Early stage disease

Early stage is anything up to 2A. Most patients have this stage of skin lymphoma when diagnosed.

Stage 1:

  • 1A means less than a tenth of the skin is affected
  • 1B means that more than a tenth of the skin is affected (roughly size of both arms)

Stage 2:

  • 2A means there are patches or plaques on the skin and the lymph nodes are enlarged but they do not contain abnormal lymphoma cells.
  • 2B means that there are one or more raised lumps or tumours in the skin and the lymph nodes may or may not be enlarged but do not contain lymphoma cells

Advanced stage disease

Stage 3:

  • 80% or more of the skin is affected, with generalised redness, swelling, itching and sometimes pain.  The lymph nodes are enlarged but do not contain abnormal lymphoma cells.
  • 3A means there are a few or no lymphoma cells in the bloodstream
  • 3B means there are moderate numbers of lymphoma cells in the bloodstream (Sezary syndrome)

Stage 4:

  • Stage 4 mycosis fungoides or sezary syndrome affects the skin and has also spread to the bloodstream, lymph nodes or other organs.
  • 4A means there are numerous abnormal lymphoma cells in the bloodstream, or the lymph nodes contain lymphoma cells.
  • 4B means the lymphoma is in other organs

Staging scans and tests

The scans and tests needed for staging and before treatment can start may include:

  • Positron emission tomography (PET) scan 
  • Computed tomography (CT) scan 
  • Bone marrow biopsy 
  • Lumbar puncture & magnetic resonance imaging (MRI) – If lymphoma is suspected in the brain or spinal cord

Patients may also undergo a number of baseline tests prior to any treatment commencing to check organ functions.  These are often repeated during and after the treatment has completed to assess whether the treatment has affected the functioning of organs.  Sometimes the treatment and follow-up care may need to be adjusted to help manage side effects. These may include:

  • Physical examination
  • Vital observations (blood pressure, temperature, & pulse rate)
  • Heart scan
  • Kidney scan
  • Breathing tests
  • Blood tests

It may take some time for all the necessary biopsies and tests to be done (an average of 1-3 weeks), but it is important for the doctors to have a complete picture of the  lymphoma and the general  health of the patient  in order to make the best treatment decisions 

Many of the staging and organ function tests are done again after treatment to check whether the lymphoma treatment has worked and the effect this has had on the body.

For more info see
Staging Scans & Tests

Prognosis of mycosis fungoides (MF)

Mycosis fungoides (MF) can be very well controlled with treatment, but it has the tendency to come back (relapse) when treatment is stopped. Most patients live normal lives and have a normal life span with this lymphoma.

Treatment of mycosis fungoides (MF)

Once all the results from the biopsy and the staging scans have been completed, the doctor will review these to decide the best possible treatment for a patient.   At some cancer centres, the doctor will also meet with a team of specialists to discuss the best treatment and this is called a multidisciplinary team (MDT)meeting.  

Doctors take into consideration many factors about the lymphoma and the patient’s general health to decide when and what treatment is required.

This is based on:

  • The stage of lymphoma
  • Symptoms (including the size and location of the lymphoma)
  • How the lymphoma is affecting the body
  • Age
  • Past medical history & general health
  • Current physical and mental wellbeing
  • Patient preferences

The standard first-line treatment for mycosis fungoides may include:

  • Topical therapies such as steroid creams, topical retinoids, chemotherapy creams or ultraviolet light therapy
  • Low dose radiation
  • Chemotherapy such as methotrexate
  • Radiotherapy to treat plaques or tumours
  • Immunotherapy such as Bexarotene or interferon-alfa

Common side effects of treatment

There are many different side effects of the treatment and these are dependent on the treatment that has been given.  The treating doctor and/or cancer nurse can explain the specific side effects prior to the treatment.  Some of the more common side effects of treatment may include:

  • Anaemia (low red blood cells carry oxygen around the body)
  • Thrombocytopenia (low platelets that help bleeding and clotting)
  • Neutropenia (low white blood cells help with immunity)
  • Nausea and vomiting
  • Bowel problems such as constipation or diarrhoea
  • Fatigue (tiredness or lack of energy

The medical team, doctor, cancer nurse or pharmacist, should provide information about:

  • What treatment will be given
  • What are the common and possible side effects for the treatment
  • What side effects do you need to report to the medical team
  • What are the contact numbers, and where to attend in case of emergency 7 days a week and 24 hours per day
For more info see
Side effects of treatment

Follow-up care for mycosis fungoides (MF)

Once treatment has completed, post treatment staging scans are done to review how well the treatment has worked.  The scans will show the doctor if there has been a:

  • Complete response (CR or no signs of lymphoma remain) or a
  • Partial response (PR or there is still lymphoma present, but it has reduced in size)

If all goes well regular follow-up appointments will be made for every 3-6 months to monitor the below:  

  • Review the effectiveness of the treatment
  • Monitor any ongoing side effects from the treatment
  • Monitor for any late effects from treatment over time
  • Monitor signs of the lymphoma relapsing

These appointments are also important so that the patient can raise any concerns that they may need to discuss with the medical team. A physical examination and blood tests are also standard tests for these appointments.  Apart from immediately after treatment to review how the treatment has worked, scans are not usually done unless there is a reason for them. For some patient’s appointments may become less frequent over time.

Relapsed or refractory mycosis fungoides (MF)

If mycosis fungoides doesn’t respond to treatment (refractory) or comes back after treatment finishes (relapses), another treatment option is:

  • Antibody treatment with alemtuzumab, brentuximab vedotin or mogamulizumab

Young, fit patients who have advanced mycosis fungoides and have not responded to other treatments might be eligible for a stem cell transplant using cells from a donor (an allogeneic stem cell transplant)

Some patients with more advanced mycosis fungoides might be asked if they would like to take part in a clinical trial

What happens after treatment?

Late Effects  

Sometimes a side effect from treatment may continue or develop months or years after treatment has completed.  This is called a late effect. 

Finishing treatment

This can be a challenging time for many people and some of the common concerns can be related to:

  • Physical
  • Mental wellbeing
  • Emotional health
  • Relationships
  • Work, study, and social activities
For more info see
Finishing Treatment

Health and wellbeing

A healthy lifestyle, or some positive lifestyle changes after treatment can be a great help after the treatment has been finished.  Making small changes such as eating and increasing fitness can improve health and wellbeing and help the body to recover.  There are many self-care strategies that can help during the recovery phase.

For more info see
Health & Wellbeing

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