Medical comorbidities in patients with lichen planopilaris, a retrospective case-control study

Background Lichen planopilaris (LPP) is a rare inflammatory lymphocyte-mediated disease of the scalp considered to have an autoimmune pathogenesis. Objectives To identify the prevalence of medical comorbidities in patients with classic LPP (CLPP) and frontal fibrosing alopecia (FFA). Methods The medical records of 206 LPP patients and 323 control patients were retrospectively reviewed for existing comorbidities. The control group consisted of 257 patients with androgenetic alopecia (ICD 9 = 704.0 or ICD 10 = L64.9) and 66 patients with actinic keratosis (ICD 9 = 702.0 or ICD 10 = L57.0). Results Systemic lupus erythematosus (SLE) was found in 4.37% of all patients with LPP (including CLPP and the FFA subtype) and in 0.31% of controls. Female patients with the FFA subtype were more likely to have SLE than controls (OR 31.034, 95% CI 2.405-400.382, P = 0.0085). Limitations This study is limited in that it is a retrospective chart review. Conclusion Female patients with FFA are significantly more likely to have SLE. Patients with LPP (including CLPP and the FFA subtype) are less likely to have diabetes. Patients with CLPP excluding FFA are less likely to have hypertension, heart disease, and hypothyroidism.