Statistical analysis

Clinicopathologic characteristics were compared between patients with HP and patients with SSP using the Student’s t-test, χ²-test or Wilcoxon rank sum test. Fleiss’ kappa was used to assess the interobserver agreement on the diagnosis, type of stromal changes, and basal crypt distortion. A kappa value < 0, 0.01 - 0.20, 0.21 - 0.40, 0.41 - 0.60, 0.61 - 0.80, and 0.81 - 1.0 is considered poor, slight, fair, moderate, substantial, and almost perfect agreement, respectively [14]. A P value < 0.05 was considered statistically significant. Statistical analysis was performed using R 2.15.2 (R Development Core Team, 2012, Vienna, Austria).