Use of polymerase chain reaction in the detection of clones in lymphoproliferative diseases of the skin.

Early-stage mycosis fungoides shows similar clinical symptoms and histological and immunophenotypical features to several benign lymphoproliferative skin disorders. We analyzed T cell receptor gamma gene rearrangement by polymerase chain reaction in the search for monoclonal lymphoid subpopulations in skin infiltrates. Totally, 283 skin biopsies (paraffin-embedded and frozen material) from patients with different malignant and reactive skin diseases were investigated. Using primers for the T cell receptor gamma chain gene, monoclonality was detected in 59 out of 66 (89%) cases of pleomorphic cutaneous lymphoma, in 60 out of 78 (77%) patients with mycosis fungoides, in 11 out of 22 (50%) cases of parapsoriasis en plaques, in five out of 35 (14%) cases of pseudolymphoma, in six out of 15 (40%) patients with lymphomatoid papulosis, and in none out of 64 patients with inflammatory skin diseases. The results show that clonal T cell population can be detected in the majority of patients with cutaneous T cell lymphoma, but the findings have to be correlated with the histological and morphological features.