Supplementary Material for: Psoriatic Alopecia: Clinical Features, Pathogenesis, and Emerging Treatment Strategies

Background: Psoriatic alopecia is a distinct but underrecognized manifestation of psoriasis, leading to both non-scarring and scarring hair loss. While scalp involvement is common in psoriasis, the mechanisms underlying follicular damage and hair loss remain poorly understood. Diagnosis is challenging due to clinical and histopathological overlap with other alopecias, and treatment responses are often variable. Summary: This review examines the clinical presentation, pathogenesis, and management of psoriatic alopecia. The inflammatory process, primarily driven by the Th17/IL-23 axis, contributes to hair follicle disruption, sebaceous gland atrophy, and in severe cases, permanent alopecia. Trichoscopy and histopathology aid in diagnosis, but standardized criteria are lacking. Treatment strategies include topical corticosteroids, vitamin D analogs, and systemic biologics, but some patients remain refractory to conventional therapies. Paradoxical psoriatic alopecia induced by TNF inhibitors further complicates management, necessitating individualized treatment approaches. Key Messages: Psoriatic alopecia requires greater clinical recognition and research to improve diagnosis and treatment. A deeper understanding of its pathogenesis, particularly immune-mediated follicular damage, could lead to more effective therapies. Personalized treatment approaches, including novel biologics, hold promise for improving patient outcomes, but further studies are needed to optimize long-term management strategies.