Learning Objective
Describe the clinical features, pathogenesis, and histopathology of granuloma annulare as a papular dermatologic condition.
Granuloma Annulare
Granuloma annulare is a chronic, benign inflammatory skin disorder characterized by papules and ring-shaped plaques. It is most commonly seen in children and young adults, although it can occur at any age.
Key Clinical Features
- Presents as firm, smooth, skin-colored to erythematous papules
- Lesions often form annular (ring-shaped) plaques with central clearing
- Common sites: dorsal hands, feet, wrists, and ankles
- Usually asymptomatic, but may be mildly pruritic
- Most cases are idiopathic and occur in healthy individuals
- Self-limiting; may resolve spontaneously over months to years
Pathogenesis
- Believed to be immunologic in origin
- Possible association with type IV hypersensitivity reactions
- Most cases occur in individuals who are otherwise healthy (no systemic illness)
Microscopic Features
- Classic finding: palisaded granulomas
- Histology shows:
- Central zone of necrobiotic collagen
- Surrounded by palisading histiocytes
- Often accompanied by mucin deposition
Management
- Usually not required due to spontaneous resolution
- Options if treatment is desired:
- Topical or intralesional corticosteroids
- Cryotherapy for localized lesions
