Primary cutaneous T-cell lymphomas

Lymphomas are tumours of the lymph nodes and lymphatic system. When the tumour occurs in the skin with no sign of involvement elsewhere in the body, they are known as primary cutaneous lymphomas; of these 65% are T-cell type. The incidence of primary cutaneous lymphomas is about 0.4 per 100,000 people per year and of these approximately two-thirds are T-cell in origin (Whittaker et al., 2003). There appears to be a higher incidence in men. There are a number of types of T-cell lymphoma which can be generally categorised into indolent (or low grade, slow growing) types or the more aggressive lymphomas. These are listed in Table 13.3; however, in this section only the most common T-cell lymphoma, mycosis fungoides (MF) (accounting for 50% of all primary cutaneous lymphomas), is considered in any detail.

Table 13.3 Types of primary cutaneous T-cell lymphoma.   Indolent   Aggressive   Mycosis fungoides (MF)   Sezary syndrome   MF variants Fulliculotrophic Pagetoid reticulosis Granulomatus slack skin   Adult T-cell leukaemia/lymphoma   Primary cutaneous CD30+ lymphoproliferative disorders   Extranodal NK/T-cell lymphoma, nasal type   Subcutaneous panniculitis-like T-cell lymphomas   Primary cutaneous peripheral T-cell   Primary cutaneous CD4+ small/medium pleomorphic T-cell lymphoma