Granuloma annulare
Granuloma annulare is a harmless, benign condition.
✅ Not infectious, not contagious, and not allergy-related.
Some forms have been linked with diabetes mellitus, though the exact cause is still uncertain.
📖 About
- Can affect all ages, but most common in children and young adults.
- Two main types:
- 🎯 Localized (most common) → rash on hands and feet.
- 🌐 Generalized → widespread rash affecting trunk and limbs.
- Often self-limiting, though persistent in some cases.
🧬 Aetiology
- Thought to represent a Type IV hypersensitivity reaction (T-cell–mediated immune response against dermal antigens).
- Associated with diabetes mellitus, thyroid disease, and rarely malignancy.
- Possible triggers: minor trauma, insect bites, infections, sun exposure.
🩺 Clinical Features
- Typically non-itchy, smooth, circular or ring-shaped lesions.
- Lesions may be skin-coloured, pink, or violaceous.
- Common sites: hands, knuckles, elbows, and extensor forearms.
- Lesions may measure up to 5 cm in diameter.
- In generalized cases → multiple plaques across trunk and extremities.
🔍 Investigations
- 🩸 Blood glucose testing → screen for diabetes mellitus.
- 🔬 Skin biopsy in atypical cases → helps distinguish from tinea corporis (ringworm).
💊 Management
- 🌿 Reassurance: condition is benign and often resolves spontaneously within months–2 years.
- Localized disease:
- Topical corticosteroids to reduce inflammation.
- Intralesional corticosteroid injections for resistant plaques.
- Generalized or resistant disease:
- Systemic corticosteroids (short courses).
- Phototherapy (PUVA or narrowband UVB).
- Hydroxychloroquine or dapsone in selected severe cases.
- Patient education:
- Reassure that lesions are not contagious 👍.
- Encourage regular follow-up, especially if associated with systemic illness (e.g. diabetes, thyroid disease).
📚 References