Serum periostin levels in mycosis fungoides: associations with clinical subtype and disease stage.

Serum biomarkers with diagnostic and staging relevance in mycosis fungoides (MF) remain limited. In this prospective case-control study, we evaluated serum periostin levels in 40 patients with MF and 40 matched healthy controls, and assessed their associations with clinical subtype and disease stage. Serum periostin was measured by enzyme-linked immunosorbent assay (ELISA), and comparisons were performed using non-parametric tests. Serum periostin levels were significantly higher in patients with MF than in controls (p<0.0001). Receiver operating characteristic (ROC) analysis demonstrated moderate discrimination for MF, with an area under the curve (AUC) of 0.77 (95% confidence interval [CI], 0.67-0.88); the optimal cut-off was 7.50 ng/mL, yielding 74.36% sensitivity and 70.00% specificity. Periostin levels also differed significantly across clinical subtypes (Kruskal-Wallis, p<0.0001), with higher levels in patch and plaque disease than in tumor-stage disease. In addition, serum periostin was significantly higher in early-stage MF (IA-IIA) than in advanced-stage disease (IIB and above) (p=0.035). These findings support serum periostin as a supportive biomarker reflecting clinical subtype and stage in MF, warranting further validation.