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Objective: The magnitude of blood involvement in cutaneous T cell lymphoma (CTCL) has prognostic significance. Several groups have proposed hematologic criteria for B ratings for use in clinical staging of CTCL, but in practice B ratings are only relevant for the staging of erythrodermic CTCL without lymph node or visceral involvement, i.e., T4N0-2M0B0 defines sub-stage IIIA, T4N0-2M0B1 defines sub-stage IIIB and T4N0-2M0B2 defines sub-stage IVA1. This retrospective study examines the effect of various B rating criteria on prognoses of patients with erythrodermic CTCL.
Methods: At initial presentation, 152 patients diagnosed with E-CTCL had quantitative Sézary cell counts performed on blood smears and CD4+/CD8- ratios determined in the blood by flow cytometry. In addition, 39 patients had percentages of CD4+CD26- and CD4+CD7- lymphocytes directly measured. The Kaplan-Meier method and Cox proportional hazards model were used to estimate mean overall and CTCL-specific survival and to compare survival curves of sub-stages of erythrodermic CTCL.
Results: With B2 rating defined as absolute Sézary cell counts ≥ 1.0 K/μL or CD4+/CD8- ratio ≥ 10, a better separation of survival curves between sub-stages IIIA and IIIB was observed if the threshold for B1 was defined as Sézary cells ≥ 20% and CD4+/CD8- ratio defined as ≥ 4 plus confirmation of blood involvement. With either criterion, the survival of patients at sub-stages IVA1 and IVA2 were not statistically different. There was also a suggestion that percentage of CD4+CD26- or CD4+CD7- cells (which ever was higher) might be used to define B1 and B2 thresholds (≥ 30% and ≥ 60%, respectively) as an alternative to absolute counts. Maximum CD4+CD26-/CD4+CD7- ≥ 30% plus confirmation also might provide a hematologic definition of leukemic CTCL.
Conclusion: Additional studies on larger number of patients and evaluation with other measures of blood tumor burden are indicated.