GENOTYPIC ANALYSIS OF CUTANEOUS T-CELL LYMPHOMA - A COMPARATIVE-STUDYOF SOUTHERN BLOT ANALYSIS WITH POLYMERASE CHAIN-REACTION AMPLIFICATION OF THE T-CELL RECEPTOR-GAMMA GENE

The diagnosis of early cutaneous T-cell lymphoma (CTCL) is a difficult point in dermatology. Recently, Southern blot analysis (SBA) and poly merase chain reaction (PCR) have been used to detect clonality in init ial lesions in which clinical and histological findings are unspecific . Forty-one samples from 25 patients with CTCL were investigated for t he presence of T-cell receptor-gamma gene rearrangement using a nested PCR technique and analysed by polyacrylamide gel electrophoresis (PAG E). Conventional SBA was also performed on 28 samples from 20 of these patients. In addition, 20 samples corresponding to patients with larg e plaque parapsoriasis (LPP), cutaneous E-cell lymphoma (CBCL) and ecz ema were analysed by PCR in the same way as were the CTCL specimens. M ost of the CTCL specimens (81%) showed clonality on PCR analysis. Amon g patients with mycosis fungoides, 71% of initial patch lesions and 10 0% of plaques and rumours showed clonal disease. Clonality could be de tected in three of four histologically negative post-treatment lesions . Clonal rearrangement was detected in one of three patients with LPP and in three of 10 patients with CBCL. None of the samples correspondi ng to patients with eczema showed positive results. SEA was significan tly less sensitive than PCR in detecting clonality in CTCL patients (4 2% among early disease and 60% among advanced cases). The results indi cate that this PCR/PAGE technique is a reliable and useful method for the detection of clonality in early skin lesions of CTCL patients and probably in the identification of silent extracutaneous involvement.