Cutaneous T-cell infiltrates: analysis of T-cell receptor gamma gene rearrangement by polymerase chain reaction and denaturing gradient gel electrophoresis.

In cutaneous T-cell infiltrates, the demonstration of a clonal T-cell receptor (TCR) gene rearrangement has been considered helpful to distinguish Cutaneous T-cell lymphomas from reactive lymphoproliferation. Hence, a polymerase chain reaction (PCR) method using GC-clamp primers and denaturing gradient gel electrophoresis has been developed in our laboratory to analyze the TCR gamma locus configuration. Two hundred eleven cutaneous samples from 155 patients were analyzed. A detectable clonal TCR gamma rearrangement was significantly associated with cutaneous T-cell lymphomas as defined by morphologic and immunologic criteria. A clonal TCR gamma rearrangement was also detected frequently in lymphomatoid papulosis, never in reactive lymphocytic infiltrates and B-cell lymphomas, and rarely in parapsoriasis en plaque and cutaneous lymphoid hyperplasia. Forty five patients had both a cutaneous and a peripheral blood sample. Fifteen had a detectable clonal rearrangement in the two samples and 22 were negative. Six patients had a positive skin sample and a negative blood sample, whereas two patients had a positive blood sample and a negative skin sample. Four lymph node samples were analyzed and the PCR results were the same as in the skin. Finally, 21 patients had sequential samples of recurrent skin lesions. The PCR results were concordant in all and, when detectable, the clonal TCR gamma rearrangement remained unchanged in a given patient. Because of its simplicity and accuracy, the newly designed PCR procedure improves the monitoring of diagnosis, staging, and follow-up in cutaneous T-cell infiltrates.