Mycosis fungoides is rare and occurs in less than 1% of all non-Hodgkin lymphomas. There are around 6 new cases per year in Norway. There is an increased incidence of mycosis fungoides observed in patients with Hodgkin's lymphoma.
The disease manifestation is often subtle. It may take several years from the first manifestation until a reliable diagnosis is determined. Skin changes may have characteristics of papules or plaque that develop into tumor or general erythrodermia.
Changes can be kept under control with years of local treatment, but normally the disease progresses to generalized disease over years. The most important prognostic factors are degree of skin involvement, elevated LDH, and thickness of cutaneous infiltrates evaluated histologically.
Sézary syndrome is diagnosed when there are atypical T cells also in other organs than skin (lymph nodes, bone marrow, blood) and when there is diffuse skin involvement (erythrodermia).
Morphologically there are small to medium lymphoid cells with irregular nuclei (cerebriform) in the skin. The lymphoid cells display epidermotropism with small accumulations of tumor cells in the epidermis (Pautrier abscesses). The different clinical presentation forms give characteristic histological changes.
The histological diagnosis is difficult and clinical information is often necessary. It is important to note that sometimes multiple biopsies are necessary before identifying typical diagnostic changes. The biopsy should be taken from the most involved area thereby minimizing the need for multiple biopsies. Rearrangement of T-cell receptor γ/δ may be helpful. It is very common for the tumor cells to be CD4-positive.
The TNM classification system is often used for staging this type of lymphoma.
TNM classification of cutaneous lymphomas
clinical or histological
||Papules and plaques, less than 10%
||Papules and plaques,
more than 10%
||Clinical pathology, histological pathology
||No atypical circulating cells
||Atypical circulating cells
The goal of treatment is to control the disease and later to prolong life with a palliative effect.
Optimal treatment through the course of the disease requires good cooperation between dermatologist and oncologist. This cooperation should be formalized at all university hospitals. It may be necessary to have a multi-regional cooperation for this rare disease group.
Early disease is treated with local forms of therapy, usually by a dermatologist. Systemic treatment is chosen for patients with refractory disease and patients with initial extracutaneous disease, and is given by an oncologist (except for treatment with retinoids and interferon). Local radiation treatment may also be given by an oncologist.
The most widespread treatment is light therapy with UV light (PUVA therapy). For Sézary syndrome, patients may benefit from photophoresis (extracorporal PUVA). The dermatology department at St. Olavs hospital is nationally responsible for this treatment in Norway. Treatment with the mustard gas derivative mustin gives complete remissions and prolongs disease-free intervals. For confined disease, but deeper lesions and no response from PUVA, local treatment with high-volt radiotherapy may be a good alternative. For extensive skin lesions, total skin electron irradiation may provide long-term remissions. In Norway, this treatment is carried out by Oslo University Hospital only.
For advanced disease requiring chemotherapy, low-dose methotrexate, chlorambucil monotherapy, or combination monotherapy is given. Interferon-a2a is registered for use for mycosis fungoides/Sézary syndrome, but the response rate is relatively low. Certain cases with very serious conditions are considered for inclusion in a study with stem cell transplantation with reduced conditioning at Oslo University Hospital. This treatment has shown promising results in small studies and may be curative.
Phase II studies with a monoclonal antibody called CAMPATH-1H reacting with the pan-T-cell antigen CD52 (MabCampath®) have shown promising effects and can be considered for use after application for reimbursement to the local welfare office. MabCampath® causes lymphopenia and danger of opportunistic infections, especially CMV reactivation. This treatment should be given by doctors with experience with this type of therapy.