The name mycosis fungoides is somewhat misleading. With such a name, it sounds as though it should describe a fungal infection. However, mycosis fungoides is actually a term that describes a cutaneous (skin) T-cell lymphoma. Essentially, this means that there is excessive proliferation of T lymphocytes within the skin. T lymphocytes are a specialised type of white blood cell that is important in the immune response to infection. Mycosis fungoides primarily affects the skin, but in rare instances, can affect other body sites. Mycosis fungoides affects more men than women, typically occurring in adults, with the majority of cases identified in the 40-60 year old age group.
The lesions of mycosis fungoides develop slowly over time. They can take several years to progress from one stage to another. In the early stages of the condition it may easily be confused with other skin diseases such as eczema and psoriasis, because the lesions start as red, dry irregular patches on the skin. As the condition progresses, the lesions thicken into plaques and the surrounding skin can become erythematous (red). Nodules may then form and the skin may become generally red. Most lesions do not progress past the plaque stage.
Biopsies can be helpful in diagnosing the condition. Microscopically, lesions in different stages have different appearances. The lesion may need to progress significantly before an accurate diagnosis can be made. In the early stages of mycosis fungoides, a biopsy tends to reveal non-specific, chronic, psoriasis-like changes. This is not particularly helpful in forming a diagnosis; and hence, multiple biopsies may be required as the lesions progress to help form a diagnosis. In the mycotic stage, an infiltrate of inflammatory cells is present in the dermis. There are also abnormal lymphocytes. In more advanced stages, there is a thick infiltrate of abnormal lymphocytes with abnormal nuclei.
Signs and Symptoms
In most people, the lesions of mycosis fungoides are the only thing that is noticed. Itching may also be present, with approximately 1 in 5 sufferers experiencing itchiness.
The cause of mycosis fungoides is unknown. It is not contagious – that is, you cannot catch it from someone with the lesions. The condition is not known to be inherited from your parents. For reasons yet unknown, the skin-associated CD4 positive T-cells proliferate in an abnormal fashion. In some cases of mycosis fungoides, the lesions may develop following a viral infection. In some people, the disorder is associated with a history of contact dermatitis.
Approximately 5% of patients with mycosis fungoides are also affected by Sezary syndrome. Sezary syndrome is described as a leukaemic form of mycosis fungoides because the malignant T cells are also found within the blood stream. There is debate as to whether Mycosis Fungoides and Sezary syndrome are separate diseases, or if Sezary syndrome is an advanced form of mycosis fungoides. Patients with Sezary syndrome have red, painful and itchy skin. Their skin may also have tumours, plaques or plaques in various places.
Staging and Prognosis
The prognosis of patients with mycosis fungoides depends primarily on the stage of the tumour. Mycosis fungoides is staged according to a system known as the tumour, node, metastasis, blood (TNMB) classification. The tumour part describes how badly the skin itself is affected by the tumour. Node is used to denote the number of lymph nodes that are infiltrated with tumour cells. The lymph nodes are often the first distant sites affected by tumour spread. Metastasis describes the number of other organs (such as the bone, brain, liver and spleen) that the tumour has spread to. The blood part of the stage describes whether or not there are tumour cells present in the blood (Sezary syndrome). Those with spread to other organs and spread to the blood generally have a much worse prognosis than those who have disease localised to the skin. The stage of the tumour (from 1-4) is determined by the TNMB system. Stage 1 tumours carry the best prognosis, and stage 4 tumours carry a worse prognosis. Mycosis fungoides and Sezary syndrome impair the function of the immune system. Hence, patients with these diseases are prone to a range of infections. These infections are serious and can be difficult to treat. Infections are a leading cause of death amongst patients with the very rare, extensive form of the disease.
No cure exists for mycosis fungoides; however, treatments may induce remission of the condition. Response to treatment varies amongst different people, and despite treatment, the lesions may persist. Evidence to suggest that treatment of the lesions can alter the prognosis of the disease is weak, however, treatment is effective at improving symptoms. Treatments are a combination of topical agents (target the skin only) and systemic treatments which can affect the entire body. Some of the available treatment options include:
- Non-pharmaceutical options: particularly during the early stages of the disease, having a good skincare routine including moisturisers can improve the hydration of the skin, making the lesions less dry.
- Steroid ointments/creams: topical corticosteroid preparations can be effectively used on an intermittent basis. Steroid preparations can help to relieve itchiness.
- Retinoids: retinoids are used topically in the treatment of mycosis fungoides. Retinoids are similar to vitamin A, and can enter the affected cells and bind to receptors that impair the expression of genes needed for replication. A drawback to the use of retinoids is toxicity to the skin at the site of application. Retinoids are highly teratogenic (can cause damage to the developing baby) and should be avoided in pregnant women. Retinoids can also be given as systemic therapy for more advanced disease.
- Nitrogen mustard: a topical form of nitrogen mustard can be used in patients with early stages of the disease that are confined to the skin.
- Phototherapy: phototherapy involves the administration of UV light to the lesions. Narrow-band UVB light is used for very early lesions, such as thin plaques. It is often administered 3 times a week for up to 8 weeks. This treatment can clear the lesions completely if caught at an early stage. After initial treatment, maintenance therapy is recommended, usually on a once-weekly basis. The main risk with UVB therapy is an increased risk of skin cancers in the future.
- Chemotherapy: a variety of chemotherapy agents can be used in the systemic treatment of mycosis fungoides, including alkylating agents, methotrexate and purine analogues. Different chemotherapy agents and combinations have varying rates of efficacy and success.
- Monoclonal antibodies: Alemtuzumab is a monoclonal antibody that targets an antigen on the affected cells. It is mainly used in elderly patients with Sezary syndrome, and it reduces the number of cancerous white blood cells in the circulation.
If you have any questions or concerns about mycosis fungoides and its treatment options, you are welcome to contact us today.