Dendritic cells may help differentiate discoid lupus erythematosus alopecia from lichen planopilaris

Introduction: Primary cicatricial alopecia (PCA) encompasses a heterogeneous group of inflammatory diseases characterized by the replacement of hair follicle structures by fibrous tissue. Discoid lupus erythematosus (DLE) and lichen planopilaris (LPP) are the most common causes of scarring alopecia. The distinction between both entities is often challenging because of significant clinical and histopathological overlap. Aim: We hypothesized that dendritic cells which are implicated in PCA pathogenesis can provide a reliable histopathological clue to distinguish between these two entities. Material and methods: In a retrospective cohort study including 51 patients diagnosed with LPP and DLE we mapped and quantified the distribution of dendritic cells. Cell count in lesional skin was performed on immunohistochemistry by using characteristic monoclonal antibodies to specific subpopulations of dendritic cells. Results: We demonstrated that almost all subpopulations of dendritic cells were highly expressed in lesional skin of discoid lupus erythematosus patients in comparison with lichen planopilaris ones. Conclusions: In the light of this observation, dendritic cells might be used as an additional clue in differential diagnosis of PCA.