Recent physiopathological insights in cutaneous lymphocytic infiltrates

The spectrum of benign cutaneous lymphocytic infiltrates (CLI) includes a variety of entities which are classified on the basis of clinicopathological findings, and of the phenotype of the predominant lymphocytic subset among the skin infiltrate. Major concern has been recelntly given to the clonality status of CLI by using highly sensitive assays based on the PCR amplification of TCR/Ig loci. These studies allowed the characterisation of clonal benighn cutaneous lymphocytic expansions. Other studies have shown evidence of oligoclonal patterns in HIV-associated CD8 cutaneous pseudolymphomas, and functionnal studies of the skin infiltrate further showed that an antigen-driven mechanism was involved in the pathogenesis of this latter entity. Finally, the knowledge in the field of CLI has been improved by the identification of antigens associated with skin-homing properties such as the so-called. Cutaneous Lymphocyte-associated Antigen (CLA) whicis expressed at the surface of most memory T cells infiltrating the dermis in inflammatory conditions.