Minimal residual disease in mycosis fungoides follow-up can be assessed by polymerase chain reaction

Background T-cell receptor (TCR) gene rearrangement analysis, i.e. T-cell clonality, using polymerase chain reaction (PCR) is a routine method used to assess the presence of a cutaneous dominant T-cell clone in mycosis fungoides (MF). Objectives To compare the outcome of cutaneous lesions of MF after treatment with the fate of the cutaneous T-cell clonality, and to determine whether minimal residual disease can be detected in patients in clinical complete remission. Methods Fifty-one patients histologically diagnosed as having MF (17 stage IA, 21 stage IB and 13 stage III) were included in this retrospective study. T-cell clonality was analysed by GC-clamp multiplex PCRgamma-denaturing gradient gel electrophoresis. Every patient had two cutaneous biopsies at least 3 months apart. The second biopsy was performed at the site of a treated lesion. Results The presence or absence of a dominant T-cell clone in the skin remained identical in 26 of the 31 (84%) patients with persistent disease. Thirteen patients with a detectable dominant T-cell clone at diagnosis went into complete clinical remission. In nine of these 13 (69%) patients, the T-cell clone was no longer detectable after treatment. The remaining four (31%) patients had an unchanged T-cell clonality. Conclusions The TCR gene rearrangement imprint is a stable and reliable tumour marker of MF disease. One-third of patients in complete clinical remission had a cutaneous molecular residual disease, the prognostic value of which will be analysed in an ongoing prospective study.