ABSTRACT
Granuloma annulare (GA) is a noninfectious granulomatous disorder characterized by palisading granuloma formation in the dermis. The exact etiology is unknown; however, a delayed-type hypersensitivity reaction to degenerated elastic fiber is suspected. In addition, the expression of cytokines (tumor necrosis factor-α [TNF-α]), metalloproteinases (MMP-2, MMP-9), and indoleamine 2,3-dioxygenase in myeloid dendritic cells and macrophages is considered a part of granuloma formation.
