Granuloma annulare: Clinical and histologic variants, epidemiology, and genetics.

Granuloma annulare (GA) is a poorly understood condition characterized by a set of clinical morphologic variants with 2 predominant histopathologic patterns of inflammation. This review provides a comprehensive overview of the available information about the clinical variants and histopathologic features, current epidemiologic data, and potential genetic underpinnings of GA. Much of the current understanding of GA is based on retrospective studies, case series, and case reports; this review aims to synthesize the available information and present it clearly for practicing dermatologists.