BH26 First reported case of lichen planopilaris in siblings: evidence for a genetic link?

Abstract Lichen planopilaris (LPP) is a primary cicatricial alopecia marked by perifollicular inflammation and progressive hair follicle destruction, ultimately leading to permanent hair loss. While its exact aetiology remains unclear, an autoimmune mechanism is suspected, with potential contributions from genetic and environmental factors. Multiple cases of familial frontal fibrosing alopecia (FFA) have been documented, and one case of LPP spanning three generations has been reported, suggesting a possible hereditary component. However, to our knowledge, this is the first documented case of LPP occurring in siblings. We report a case of histologically confirmed LPP in a brother and sister, aged 20 years and 24 years, who developed the condition within a year of each other. Both siblings displayed classic LPP features, including perifollicular erythema, follicular hyperkeratosis and progressive scarring alopecia, primarily affecting the vertex and parietal scalp. Trichoscopy findings were consistent with LPP, showing perifollicular scaling and a loss of follicular openings. A family history of autoimmune disease (hypothyroidism) was noted, and one sibling had coeliac disease. Neither had a history of known external triggers, such as hormonal therapy or excessive ultraviolet protection product use. These findings suggest a potential genetic predisposition, supporting the hypothesis of inherited susceptibility in LPP, as seen in familial cases of FFA. This case underscores the need for further genetic and immunological research to better define hereditary links in LPP and its connection to other lichenoid disorders. Identifying hereditary patterns could facilitate earlier diagnosis and targeted management in at-risk individuals.