Background: Folliculotropic mycosis fungoides (FMF) is a rare cutaneous malignancy that can be mistaken for inflammatory diseases, such as discoid lupus erythematosus (DLE), due to the variability of histopathological findings.
Methods: This study aims to provide dermatopathologists with evidence-based histopathologic criteria to distinguish DLE from FMF by reporting overlapping and distinguishing microscopic features. Forty-three biopsies from patients with a confirmed diagnosis of DLE or FMF were graded for the presence or absence of 18 histopathologic features.