Histopathologic Characterization of Lichen Planopilaris, Frontal Fibrosing Alopecia, and Central Centrifugal Cicatricial Alopecia

Intro Lichen Planopilaris (LPP), Frontal Fibrosing Alopecia (FFA) and Central Centrifugal Cicatrical Alopecia (CCCA) are a lymphocytic group of primary cicatricial alopecias (PCA) that are often histologically and immunophenotypically indistinguishable. When left untreated, they result in irreversible hair loss that often results in mental anguish and disturbed self-perception. Clinical overlap of symptoms such as scalp pain or pruritus, follicular hyperkeratosis and perifollicular erythema often require the involvement of characteristic sites and scalp biopsy to make a more definitive diagnosis. Overlap in histopathologic features limits current diagnostic evaluation but also alludes to a common pathomechanism with potential clinical implications. Due to the lack of any controlled study regarding the treatment of these PCAs, current treatment is guided by available case reports and expert opinion. These options with varying efficacy include the use of steroids, calcineurin inhibitors, 5α-reductase inhibitors, Janus Kinsase (JAK) inhibitors, hypoglycemic drugs, and over the counter products. The purpose of this study was to characterize histopathologic similarities between LPP, FFA, and CCCA in order to better define these entities and guide therapeutic targets. Methods A minimum of 25 histologically confirmed cases of LPP, FFA, and CCCA H&E slides were re-examined by a trained dermatopathologist to investigate the common histological findings. Results All across LPP, FFA, and CCCA, there were features of lymphocytic infiltrate particularly around the mantle zone area along with perifollicular fibrosis. The inflammatory infiltrates predominantly consisted of lymphocytes, and the only presence of neutrophils was secondary to rupture of follicles. Conclusion To our knowledge this is the largest case series comparing histological features of LPP, FFA, and CCCA. As these three alopecia exhibit similar pathological changes, it may suggest that they are clinical variants of the same disease process. Current data in the literature has yet to demonstrate a consensus on content of lymphocytic infiltrate and trigger for lymphocytic migration. Future direction of treatment innovations should thus focus on early detection, prevention of scalp trauma, and therapies that target early lymphocytic changes.