Detection of a peripheral blood T cell clone is an independent prognostic marker in mycosis fungoides

Abstract

T cell receptor gene analysis is a sensitive method for assessment of peripheral blood involvement in mycosis fungoides. This study uses polymerase chain reaction/single-strand conformational polymorphism (PCR/SSCP) analysis of the T cell receptor γ gene and relates the results to skin stage and outcome in mycosis fungoides. Seventy-five peripheral blood samples from 66 patients were obtained from 1990 onwards and subjected to PCR/SSCP. Both Southern blot analysis and PCR/SSCP analysis were performed on 63 samples from 56 patients. Fourteen patients had T1 disease (12 IA, two IIA), 20 T2 (14 IB, five IIA, one IVA), 29 T3 (24 IIB, two IVA, three IVB, two patients tested at both T2 and T3), and five T4 (all III). The percentage of positive samples was higher with PCR/SSCP than with Southern blot analysis (29 of 63 vs eight of 63 samples, p < 0.001), and the percentage of positive samples increased with each stage (21% at T1, 35% at T2, 58% at T3, and 71% at T4). Proportional hazards analysis corrected for age, skin, and lymph node stage showed that the presence of a peripheral blood clone is associated with a worse outcome (p=0.03, CI 1.1-6.03). These results indicate that the presence of a peripheral blood clone is an independent prognostic variable in patients with mycosis fungoides after correcting for age, skin, and lymph node stage, and that peripheral blood involvement is present in a large proportion of patients with early stage mycosis fungoides.