Classic Lichen planopilaris and pseudopelade of Brocq of the scalp: a retrospective study of epidemiological, histopathological and etiopathogenetic differences.

Background: Lichen planopilaris (LPP) and pseudopelade of Brocq (PPB) are lymphocytic scarring alopecias that commonly involve the scalp with alopecic patches and can be considered as a unique nosologic condition. The medical features of patients affected by scalp Lichen planopilaris were reviewed to identify demographic differences between the classic LPP (C-LPP) and the pseudopelade of Brocq variant (PB-LPP).

Methods: A retrospective analysis of patients with classic Lichen planopilaris (C-LPP) and the pseudopelade of Brocq variant (PB-LPP) was conducted. Demographic and clinical data, results of trichoscopy and histopathology were analyzed.

Results: Sixty patients with LPP were followed up from March 2020 to March 2023. The mean age of the population at the time of the analysis was 63.1 years, and the mean age at clinical or histological diagnosis of LPP was 60.1. The predominant sex was female. The clinical-histological diagnosis of PB-LPP was reported in four patients (6.7%), the remaining presented a variant of C-LPP. No significant differences between the two variants of LPP concerning mean patient age and age at diagnosis was found. PB-LPP was more frequent in the male gender than in the female gender. No difference was observed for concomitant autoimmune diseases.

Conclusions: Our study confirms a prevalence of classic Lichen planopilaris in female patients and a predilection for the pseudopelade of Brocq LPP in the male patients. However, due to the low number of cases due to rarity of diseases, more studies are needed to confirm our data and hypotheses.