Clinical, Trichoscopic, and Histopathological Features of Primary Cicatricial Alopecias: A Retrospective Observational Study at a Tertiary Care Centre of North East India.

BACKGROUND: The primary cicatricial alopecias (PCAs) are a rare group of diseases where hair follicle is the primary target of destruction. There are a few studies on histopathological and trichoscopic features of PCA.

AIMS: To study the clinical, trichoscopic, and histopathological characteristics of PCAs of the scalp and to find out the concordance between trichoscopic and histopathological diagnosis.

MATERIALS AND METHODS: We retrospectively analyzed the clinical, trichoscopic, and histopathological features of 24 PCA patients. Fisher's Chi-square exact test was done to find the significant trichoscopic and histopathological features. Cohen's kappa coefficient was used to determine the agreement between histopathological and trichoscopic diagnosis.

RESULTS: A total of 24 patients of PCA were seen with a male: female ratio of 2:1. There were 10 (41.7%) patients of discoid lupus erythematosus (DLE), 5 (20.8%) of lichen planopilaris (LPP), 3 (12.5%) of dissecting cellulitis of scalp, and 2 (8.3%) each of pseudopelade of brocq, folliculitis decalvans, and frontal fibrosing alopecia. The important histopathological findings of DLE were follicular plugging, vacuolar changes in the basal layer, necrotic keratinocytes, and superficial and deep perifollicular and perivascular lymphocytic infiltrate. Histopathology of LPP showed vacuolar changes in the basal layer and lichenoid infiltrate involving the infundibulum and isthmus. Trichoscopy of DLE showed follicular plugging, yellow dots, and thick arborizing blood vessels. The peripilar cast was important finding in LPP. The characteristic yellow dot with three-dimensional structure was noted in dissecting cellulitis of the scalp. The Cohen's kappa agreement was 0.89 between histopathological and trichoscopic diagnosis.

CONCLUSION: The diagnosis of PCA is challenging because of overlapping features clinically and histopathologically. Trichoscopy may provide quick and reliable diagnosis and obviate the necessity of scalp biopsy in busy clinics.