TEMPERATURE-GRADIENT GEL-ELECTROPHORESIS FOR ANALYSIS OF A POLYMERASE CHAIN REACTION-BASED DIAGNOSTIC CLONALITY ASSAY IN THE EARLY STAGES OF CUTANEOUS T-CELL LYMPHOMAS

By means of a multiplex polymerase chain reaction (PCR) we amplified rearranged T-cell receptor gamma chain genes to detect monoclonality in 370 formalin-fixed skin biopsy specimens, showing histological features of parapsoriasis or mycosis fungoides. PCr products were analyzed by temperature gradient gel electrophoresis (TGGE). We selected 20 positive cases for use in a comparison of this technique with conventional agarose and polyacrylamide gel electrophoresis (PAGE). With TGGE the T-cells had shown monoclonality in 272 of the 370 cases; with agarose electrophoresis they did so in only 5 of the 20 selected cases and with PAGE in 16. Where multiple biopsy specimens from the same patient were analyzed, PCR products showed identical rearrangement patterns in TGGE. TGGE is an efficient technique that works on routine material and can help to verify a histological diagnosis of cutaneous T-cell lymphoma.