Mycosis fungoides rash is a type of lymphoma very difficult to diagnose, meaning quite an aggressive cancer. If the diagnosis is early, life expectancy is long.

Mycosis fungoides is the most common form of cutaneous T-cell lymphoma, a type of white blood cell. A lymphoma is a neoplastic formation, in this case it affects the skin and usually manifests itself by skin redness, with different stages of evolution.

Doctors base the diagnosis on a tissue sample or biopsy that will they later analyze. Depending on the stage, the prognosis and therapeutic options will be one or the other.

Although doctors use the term mycosis often to speak of infections due to fungi, in this case we are talking about a lymphoma, that is, a neoplastic or cancerous proliferation. Lymphomas are neoplasms due to lymphocytes (blood cells that are part of the immune system) which are malignant.

There are two types of lymphocytes. These are B lymphocytes and T lymphocytes. In mycosis fungoides, the malignant lymphocytes are T lymphocytes, which grow in lymphoid organs and affect the skin.

Lymphoma or leukemia?

Doctors use both terms to talk about neoplasms that affect blood cells. The main difference between leukemia and lymphoma is where the malignant cells are:

In leukemias, malignant cells appear in peripheral blood and in the bone marrow, where all blood cells are made.

In lymphomas, malignant cells are in lymphoid organs, such as lymph nodes, with a low presence in blood and bone marrow. Lymph nodes are small, oval structures that are part of the immune system and are distributed throughout the body.

Although leukemia and lymphoma are different terms, doctors do not always differentiate them well in practice. Lymphomas “leukemize” when cancer cells appear in the blood. Similarly, in leukemias, cancer cells can appear in lymph nodes.

The leukemic form of mycosis fungoides is Sezary syndrome. Mycosis fungoides and Sézary syndrome are diseases in which lymphocytes (type of white blood cells) become malignant (cancerous) and affect the skin.

Mycosis fungoides rash

There are several types of evolutionary stages in the development of mycosis fungoides rash, although they do not always appear or follow this sequence:

  • Premychotic phase: diagnosis in this phase is difficult since only a skin rash appears. The skin becomes red in some areas without following a clear pattern. In addition, it does not usually produce symptoms of any kind.
  • Patchy phase: The skin rash is similar to eczema like that found in some types of dermatitis. Reddened skin becomes inflamed and may peel, causing severe itching or itching.
  • Plaque phase: Lesions rise and form papules, may remain red, and are often hard to the touch.
  • Tumor phase: the plaques become tumors, that is, masses of abnormal cells. Depending on the aggressiveness and the time of evolution, they can become infected or ulcerate.

If Sezary syndrome is present, the distribution of lesions may be generalized, with pain and burning, stinging, and possible scaling.


The physical examination of the patient is key to any diagnosis. Each lesion must be examined separately and asked about their evolution and how they appear.

Since not all patients evolve in the same way, a blood test and a skin biopsy are essential.

Blood study: it must include a complete blood count, that is, a count of each type of blood cell. It is very useful as it informs about the type of cell that is proliferating. You may also do a peripheral blood smear which, in the case of leukemias, will show the abnormal cells.

Skin biopsy: taking the skin lesions and their subsequent microscopic analysis will give us the diagnosis of mycosis fungoides.

Evolutionary stage

Once we have the diagnosis, it is important to determine the evolutionary stage of mycosis fungoides. In other words, you have to find out to what degree the cancer affects the rest of the body.

Obviously, the greater the tumor spread, the worse the prognosis will be for the patient. Four stages are distinguished:

Stage I:

  1. The affected surface is less than 10% of the body surface and only spots or papules appear.
  2. The affected area is greater than 10%, but only spots or papules appear.

Stage II:

IIA. In addition to skin involvement, the lymph nodes are swollen. In other words, there are adenopathies, but they do not contain tumor cells.

IIB. Tumors appear on the skin. Its length is at least 1 cm and if there are adenopathies, they do not contain tumor cells.

Stage III: Most of the skin is red and with spots, plaques or tumors. The cancer has not infiltrated the lymph nodes.

Stage IV:

IVA: It affects most of the skin as well as the lymph nodes.

IVB: The skin condition is generalized and the tumor has also spread to other organs. Lymph nodes may or may not be infiltrated, there may also be malignant lymphocytes in the blood.

Prognosis of the disease

The prognosis of the disease depends on the general condition of the patient, the specific characteristics of the tumor cells and the evolutionary stage.

In general, both mycosis fungoides rash and Sezary syndrome are diseases that are difficult to cure; treatment is usually palliative. Even so, if the diagnosis is early, life expectancy is long. Patients diagnosed with stage I have a median survival of 20 years.

The main factors of poor prognosis are the following:

  • Stage IV diagnosis.
  • More than 60 years.
  • Cell transformation to large cells.

Elevated lactate dehydrogenase (LDH) concentrations. It is a marker of cell replication, every time a cell divides, it produces LDH. So the more tumor cells divide, the more aggressive the tumor will be, and the more LDH will rise.

The treatment of mycosis fungoides is usually on the basis of a symptomatic treatment. It is on the basis of radiotherapy, chemotherapy, photodynamic therapy (lasers of different types to eliminate tumor cells), biological therapy and certain drugs.

Of course, you would need to get a doctor’s opinion, in order to treat this disease properly. Naturally, you’ll also need to have a support group to help you get through it. Support is important with any type of cancer, so make sure you have it. And remember, as long as you’ve discovered it on time, you’ll probably get rid of it in no time. Just do what your doctor says, think positive, and things will work out.

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