Modern diagnosis of cutaneous lymphoma

The issue of primary cutaneous lymphoma (CL) has been greatly influenced by the increasing knowledge about lymphoid cell biology, the widespread use of sensitive and specific immunological and molecular markers, and the careful correlation among clinical, histological and immunomolecular features. This latter is the key element of the classification of CL proposed by the EORTC Cutaneous Lymphoma Study Group in 1997, which categorizes distinct clinicopathological entities with prognostic and therapeutic relevance. With few exceptions, no reliable diagnosis and subtyping of CL can be made without the aid of immunohistochemistry and/or molecular analysis. On the other hand, the acritical use of immunological and molecular markers can be misleading if not combined properly with a correct clinical and histological evaluation. For this reason, a step-by-step diagnosis and staging protocol is exceedingly important. Finally, great caution should be used in the interpretation of lymphoid cell infiltrates of the skin which show a monoclonal rearrangement in the absence of reliable clinical and/or pathological evidence of neoplasia.