Cutaneous T-cell lymphomas (CTCL) belong to the extranodal non-Hodgkin's lymphomas. The incidence is 0.5-1/100,000. Mycosis fungoides (MF, Fig. 14.1), the most common, and Sezary syndrome (SS), a leukaemic variant, are discussed in more detail. Another group of CTCL are the CD30+ lymphoproliferative disorders, nominally anaplastic large cell lymphoma and lympho-matoid papulosis, which are characterized by a relapsing course but an overall favourable prognosis. All other entities of CTCL are rare.
For MF the mean age of manifestation is 55 years with a male predominance of 2:1. While the life expectancy for patients with limited skin involvement equals that of a healthy control group, the 5-year survival rate for patients with lymph node involvement falls to 20%.
Despite intense research, the exact pathogenesis of CTCL is still not understood. In immunohistochemis-try the malignant cells are of a CD4+ T-cell memory phenotype, and the loss of certain T-cell markers like CD2, CD3 or CD5 is a common finding. However, in initial stages of the disease it can be impossible to differentiate between the clonal T cells and concomitantly infiltrating lymphocytes by microscopy.
The histological hallmark of early MF is the so-called Pautrier microabscess. These are composed of T cells and Langerhans cells, the epidermal antigen presenting cells. Therefore chronic stimulation with a, so far unknown, antigen is thought to result in uncontrolled proliferation of MF/SS cells. Possible triggers may be antigens, derived from the atypical T cells themselves as well as bacterial superantigens.
The clinical picture of MF is characterized by patches, plaques and tumours, which may occur separately as well as concomitantly. The latter may have a mushroom-like appearance, which is responsible for the term mycosis fungoides.
As there has been no curative therapy hitherto, the treatment of CTCL is stage adapted. While therapy in early stages without extracutaneous involvement is skin directed, e.g. topical steroids, topical chemotherapy or phototherapy, in more widespread disease a combination of topical therapy with systemic agents such as interferons and/or retinoids is advisable. Chemotherapy should be reserved for late stages of MF with visceral involvement as it results in selection of therapy-resistant tumour cell clones in most cases.
Seezary syndrome is a CTCL defined by erythroder-ma, a leukaemic phase and lymph node involvement at the time of diagnosis. Additional morphologic features are an often-intense pruritus and palmoplantar hyper-keratosis. In contrast to MF the prognosis for SS is much worse, with a 5-year survival rate of only 24%.
Therapy with extracorporeal photopheresis (ECP) alone or in combination with interferon- has been shown to induce complete remission. The ECP is a procedure during which leukocytes are separated from red blood cells, and are, after incubation with psoralen, radiated with UV light. The procedure results in lymphocyte apoptosis while monocytes differentiate into immature dendritic cells (DC). The effect of ECP is possibly mediated by maturation of DC after ingestion of apoptotic lymphocytes, resulting in presentation of tumour cell derived antigen to cytotoxic T cells. Thereby an anti-tumour immune response is generated. An alternative first line therapy is a combination of PUVA and interferon- . However, in advanced disease only single or multiagent chemotherapy may be able to, at least transiently, stop disease progression.
Was this article helpful?
Do You Suffer From the Itching and Scaling of Psoriasis? Or the Chronic Agony of Psoriatic Arthritis? If so you are not ALONE! A whopping three percent of the world’s populations suffer from either condition! An incredible 56 million working hours are lost every year by psoriasis sufferers according to the National Psoriasis Foundation.