Granuloma annulare: An updated review of epidemiology, molecular pathogenesis, and management

Granuloma annulare (GA) is an inflammatory skin disease typically characterized by an erythematous eruption consisting of papules and annular plaques. GA can have a severe impact on quality of life, especially when widespread. GA can be difficult to treat and often recurs after treatment is stopped; there remain no Food and Drug Administration‑approved therapies. In recent years, there has been significant progress in understanding the epidemiology, disease associations, and molecular pathogenesis of GA. Patients with GA are more likely to have hyperlipidemia, diabetes mellitus, and autoimmune diseases including thyroiditis, rheumatoid arthritis, and systemic lupus erythematosus. These associations further underscore the importance of recognizing GA and evaluating for comorbid disease. Accurate diagnosis of GA requires distinguishing it from its clinical and histologic mimics, some of which share annular morphology or granulomatous inflammation. Molecular work has suggested a T cell‑mediated pathogenesis and identified key cytokines and other signals that drive macrophage accumulation and activation in tissue. Emerging therapies that block these cytokine signals are showing promise in the clinic. In this article, we provide an updated overview of the epidemiology, disease associations, clinical and histopathologic characteristics, molecular pathogenesis, and treatment of GA.