Diagnostic value of dominant T-cell clones in peripheral blood in 363 patients presenting consecutively with a clinical suspicion of cutaneous lymphoma

It is now widely accepted that polymerase chain reaction (PCR) analysis of cutaneous T-cell clonality is of diagnostic value in cutaneous T-cell lymph omas (CTCLs) and most helpful in the diagnosis of mycosis fungoides (MF), H owever, the diagnostic and prognostic value of circulating clonal T cells r emains unclear. We studied T-cell clonality in the peripheral blood (PB) an d the cutaneous lesion, sampled at the same time, in 363 consecutively seen patients with a clinical suspicion of cutaneous lymphoma. Using a PCR tech nique providing a specific imprint of T-cell clones (PCR gamma -denaturing gradient gel electrophoresis), we found that detection of identical circula ting and cutaneous T-cell clones was associated with the diagnosis of CTCL (P < .001), Detection of circulating tumor cells in patients with MF was in frequent (12.5%), except in those with erythrodermic MF (42%; P = .003), Mo reover, among the 46 patients who had identical circulating and cutaneous T -cell clones, 25 (56%) had erythroderma, The finding of a dominant clone in the PB but not in the skin was frequent, regardless of the clinicohistolog ic classification; it occurred in 30% of patients with CTCL, 41% with non-C TCL malignant infiltrates, and 34% with benign infiltrates. This pattern wa s significantly more frequent in patients over 60 years of age (P < .002), even in the CTCL group (P < .01), In conclusion, dominant T-cell clones det ected in the PB of patients with MF by using a routine PCR technique are ra rely tumoral and are more often related to age. A multicenter prospective s tudy is under way to establish the prognostic value of circulating tumor ce lls. (C) 2000 by The American Society of Hematology.