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Mycosis Fungoides - Causes, Symptoms, Diagnosis and Treatment

Published on Apr 07, 2022 and last reviewed on Sep 20, 2022   -  5 min read


Mycosis fungoides is a cancerous condition with skin rash as the first sign. This article describes in depth its causes, clinical features, signs, diagnosis, and management measures.

What Is Mycosis Fungoides?

Cutaneous T-cell lymphoma or T-cell lymphoma of the skin, a form of non-Hodgkin’s lymphoma, is a type of blood cancer. And mycosis fungoides remains to be the most common form of cutaneous T-cell lymphoma. T-cells, otherwise known as lymphocytes, are a type of white blood cells that play a key role in immunity. These cells become malignant, causing T-cell lymphomas. Hence, mycosis fungoides can also be regarded as cancer of the immune system. It is otherwise known as granuloma fungoides.

Mycosis fungoides, being a cutaneous lymphoma, affects the skin to cause lesions. Though the skin is involved, the skin by itself is not malignant but is being affected.

It is a rare form of T-cell lymphoma of the skin. Mycosis fungoides affect the skin to cause plaques and nodules composed of lymphocytes. In advanced conditions, the disease spreads to the lymph nodes and other parts of the body.

What Are the Symptoms of Mycosis Fungoides?

The signs and symptoms caused by mycosis fungoides is classified into four stages, namely,

  • Stage 1.

  • Stage 2.

  • Stage 3.

  • Stage 4.

Stage 1 - This is the initial stage where mycosis fungoides cause the first sign of the disease, which is generalized itching or pruritus. It is accompanied by pain in the affected regions of the skin. Erythematous patches occur on the skin over the trunk and extremities such that they can be confused with other skin lesions like psoriasis, eczema, lichen planus, etc. People also have difficulty falling or staying asleep.

Stage 2 - This stage is otherwise known as the plaque or infiltration stage. The plaques on the skin are bluish red and circular or oval. They begin as small and elevated lesions, but over time they tend to get big and join with each other to form enlarged lesions resembling exfoliative dermatitis. The skin over the buttocks is affected.

Stage 3 - This is the tumor or fungoid stage where tumors on the skin develop. These tumors are lobulated, resembling mushrooms. These tumors get ulcerated. They range from bluish to reddish-brown and measure 0.5 inches to 6 inches in diameter. At this stage, the lymphoid cells enter the upper and lower layers of the skin and cause necrosis.

Stage 4 - At this stage, the lesions begin to spread throughout the body affecting the internal organs like the heart, brain, liver, etc. The affected person feels sick and weak. Signs and symptoms of mycosis fungoides at this stage include dysphagia, fever, weight loss, anemia, intestinal ulceration, cough, liver and spleen enlargement, vision loss, eye pain, etc.

How Does Mycosis Fungoides Cause Skin Lesions?

Mycosis fungoides gradually progress through each stage and result in increasing severity of skin lesions starting from flat lesions, raised lesions or plaques, to nodules or tumors on the skin. The cancerous T-cells are found in these lesions, which reach the skin layer from the blood. Therefore the skin by itself is not cancerous and exhibits only the lesions caused by the circulating cancerous T-cells.

  • Patch Stage - Initially, people develop flat, scaly, patchy, and itchy skin lesions that are pinkish-red. These can disappear, reappear, or persist throughout. Such patches are more commonly found on the breasts, thighs, and lower abdomen region.

  • Plaque Stage - In people where lesions progress to the next stage, plaques (raised lesions) tend to form that are reddish or brownish. These plaques may develop on their own, or a patch can transform into a plaque.

  • Tumor Stage - In the next stage, these patches and plaques may or may not develop into tumors. These tumors may ulcerate and cause open and infected sores. Commonly such tumors are found on the buttock, breast, groin, and armpit regions.

Not all patches in the affected individuals progress to form plaques and tumors. Once it reaches the tumor stage, there are high chances that the tumor spreads to lymph nodes and other organs like the liver, lungs, etc., and develop another lymphoma or another kind of tumor.

How Does Mycosis Fungoides Occur?

The cause for mycosis fungoides is not clearly understood. But studies have hypothesized the following to be the causes;

  • Exposure (occupational or environmental) to chemicals, solvents, and carcinogenic substances.

  • Higher levels of cytokines, especially interleukins such as IL-2 and IL-4.

  • Genetic abnormalities like deletion and translocations in chromosomes and their segments.

  • Exposure to human T-lymphotropic virus Type 1 (HTLV-1).

  • Inheriting HLA class 2 genes with certain variations.

Who Are More Prone to Mycosis Fungoides?

Males are twice more likely to get affected than females. Also, people aged 50 years and above are likely to get affected. Every year nearly 3.6 million people in the United States are known to get affected by this disease.

What Is Sezary Syndrome?

Sezary syndrome is often misunderstood, and the terms mycosis fungoides and Sezary syndrome are interchangeably used. But both are different conditions. In Sezary syndrome, abnormal young red blood cells or reticulocytes are known to cause lesions similar to that of mycosis fungoides. This syndrome also causes redness of the skin, itching, and swelling. There is also hair loss and hyperkeratosis, with some areas of the scaly skin falling off.

How Is Mycosis Fungoides Diagnosed?

The following diagnostic methods are recommended:

  • Physical Examination:

During a physical examination, the skin lesions will be evaluated to determine the extent of involved body surface area, type, ulceration present or not, the number of nodules or tumors, size, and site. Lymphadenopathy and splenomegaly will also be checked.

  • Biopsy:

  • Skin biopsy from the affected skin with indurated lesions will be selected, retrieved, and sent for immunophenotyping.

  • An excisional biopsy of the suspicious lymph node will be performed. Mostly cervical, axillary, and inguinal lymph nodes are preferred.

  • Blood Examination:

Complete blood count, liver function test, lactate dehydrogenase (LDH) test, T-cell receptor gene rearrangement testing, and abnormal lymphocyte count are done.

  • Radiological Examination:

Chest X-ray, chest CT (computed tomography), MRI (magnetic resonance imaging), and FDG-PET scan (fluorodeoxyglucose positron emission tomography) will be done to assess the involvement of any internal organs and lymph nodes.

How Are Mycosis Fungoides Treated?

For people in the initial stages of the disease, the following treatment options are suggested;


  • Topical corticosteroids.

  • Topical nitrogen mustards (mechlorethamine, HN2).

  • Topical Bexarotene.

  • Imiquimod.

  • Psoralen - Ultraviolet A (PUVA) therapy or ultraviolet B (UVB) therapy.

  • Local radiation therapy.

  • Total skin electron beam therapy.


  • Retinoids.

  • Interferons.

  • Histone deacetylase (HDAC) inhibitors.

  • Low-dose Methotrexate.

In the advanced stages of the disease, the following treatment methods are recommended to relieve symptoms, prevent the progression of the disease into its aggressive form, and control the disease.

  • Localized radiation to the tumors in addition to skin-directed therapy.

  • Total skin electron beam therapy.

  • Targeted immunotherapy.

  • Systemic Methotrexate, Bexarotene, etc.

  • Allogeneic hematopoietic cell transplantation.


People with mycosis fungoides diagnosed and treated in the early stages have high possibilities of long-term survival, but once the condition progresses to an advanced stage before diagnosis and treatment, survival rates remain low. Do not ignore any newly developing skin lesions. Book an online consultation with a specialist now.

Last reviewed at:
20 Sep 2022  -  5 min read




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