Revisiting Diffuse Unpatterned Alopecia: Reappraisal of a Controversial Diagnosis.

BACKGROUND: Diffuse unpatterned alopecia (DUPA) is an uncommon and incompletely characterized variant of androgenetic alopecia (AGA) marked by diffuse follicular miniaturization across the entire scalp, including the occipital region, which distinguishes it from classic patterned AGA and often precludes hair transplantation. SUMMARY: In this review of the available literature on DUPA, we discuss its clinical presentation, diagnostic features, competing pathophysiologic hypotheses, and management considerations. Current evidence suggests DUPA typically presents with diffuse thinning across all scalp regions, with trichoscopy demonstrating widespread follicular miniaturization without features of scarring alopecia. Diagnosis remains clinical because histopathologic criteria and standardized trichometric thresholds have not been established. Important mimickers include telogen effluvium and diffuse alopecia areata, requiring careful history, examination, trichoscopy, and occasional scalp biopsy. Management is primarily medical, emphasizing stabilization rather than regrowth, and includes topical or oral minoxidil with consideration of adjunctive therapies in selected patients. KEY MESSAGES: DUPA is a diffuse, non-patterned hair loss condition affecting the entire scalp, including the occipital region, for which medical management remains the cornerstone of treatment. DUPA remains poorly defined and further clinicopathologic, trichometric, and longitudinal studies are needed to clarify major knowledge gaps, including epidemiology, pathology, diagnostic criteria, and treatment-specific outcomes.