What is actinic granuloma?
Actinic granuloma is an uncommon skin disease that presents with asymptomatic annular (ring-shaped) plaques on sun-exposed sites.
It occurs most often in fair skinned middle-aged women living in sunny climates. There is debate around whether it is a distinct entity or a variant of granuloma annulare.
It is also known as O'Brien granuloma after the physician that first described it.
What is the cause of actinic granuloma?
Actinic granuloma is thought to be inflammatory response to sun damage, possibly to injured elastic fibres. The white cells known as Helper T-lymphocytes are predominantly involved.
What are the clinical features of actinic granuloma?
Actinic granuloma begins as flesh-coloured or pink papules (small bumps) which coalescence into annular plaques (larger thickened patches) ranging in size from 1 to 10 cm in diameter. The plaques typically have raised red borders and a slightly thinned, pale central area.
The lesions do not usually result in symptoms, but when exposed to the skin they may become red and uncomfortable.
How is actinic granuloma diagnosed?
The clinical diagnosis of actinic granuloma is suspected when there is an annular dermal plaque in sun exposed skin. Diagnosis is often supported by typical histopathological features on skin biopsy.
Differential diagnosis of actinic granuloma
Actinic granuloma is difficult to distinguish from other granulomatous disorders, particularly granuloma annulare and necrobiosis lipoidica.
What is the treatment of actinic granuloma?
Sun protection is important to reduce the chance of further lesions.
Treatment of actinic granuloma can be difficult. Infiltration of corticosteroids into the raised edge, phototherapy, and antimalarials are largely ineffective.
Isotretinoin and acitretin have been used with varying success and there are case reports of success with ciclosporin.