Introduction: Alopecia areata incognita (AAI) represents a distinct subtype of alopecia areata (AA), characterized by profound hair shedding and diffuse thinning. Despite being initially described in 1987, AAI remains underdiagnosed, with limited published reports. This comprehensive review aims to consolidate the current evidence concerning AAI pathogenesis, clinical presentation, trichoscopic and histopathologic attributes, differential diagnoses, and available treatment modalities.
Methods: PubMed searches were performed to identify all articles discussing AAI published up to September 2024.
Results: We identified 28 articles encompassing AAI epidemiology, pathogenesis, clinical presentation, trichoscopic findings, histopathologic characteristics, diagnosis, and treatment options.
Limitations: The data primarily stem from observational studies, case reports, case series, and a pilot study. The establishment of diagnostic criteria and treatment protocols necessitates more extensive and well-controlled studies.
Conclusion: Alopecia areata incognita is a distinctive form of AA, sharing similarities with telogen effluvium (TE) and showing potential associations with androgenetic alopecia (AGA). It has an acute onset and results in sudden diffuse hair loss. While diagnostic challenges persist, combining clinical, trichoscopic, and histopathologic evaluations aids in accurate identification. AAI typically responds favorably to topical steroids and has a better prognosis than other subtypes of AA.
Keywords: Alopecia areata; Alopecia areata incognita; Diffuse alopecia areata; Diffuse hair loss; Treatment; Trichoscopy.
© 2025. The Author(s).