Assessing the utility of incorporation of clinical and histopathologic features for risk stratification in plaque-stage folliculotropic mycosis fungoides: A retrospective validation study.

Abstract

A recently proposed staging system for folliculotropic mycosis fungoides (FMF) used clinical and histopathologic data to define 2 prognostic classes (ie early, advanced) for plaque-stage disease. In this external retrospective single-center cohort, we assessed the prognostic ability of the proposed re-classification system and high-risk histopathologic features overall. Patients with FMF were staged clinically. Skin biopsy specimens were reviewed for high-risk features. Patients with plaque-stage FMF were subcategorized as having early or advanced disease. Of 81 patients with FMF (early-stage, n = 43; advanced-stage, n = 38), 40 had plaque-stage FMF (early plaque-stage, n = 24; advanced plaque-stage, n = 16). There was no difference in overall survival between early and advanced plaque-stage FMF. Of all cases, univariate analysis revealed associations between angioinvasion/angiodestruction and overall survival (hazard ratio, 6.04; 95% CI, 1.88-19.42; P = .003) and disease-specific survival (hazard ratio, 7.17; 95% CI, 1.76-29.33; P = .006), and between large cell transformation and disease-specific survival (hazard ratio, 4.91; 95% CI, 1.47-16.35; P = .010). Few disease-specific deaths in the plaque-stage subgroup precluded analysis of disease-specific survival. In this cohort, addition of histopathologic data to subdivide plaque-stage FMF into early and advanced groups added no prognostic value. However, certain histopathologic features including angioinvasion/angiodestruction and large-cell transformation did offer prognostic power overall.