Actinic granuloma

Actinic granuloma is a rare, idiopathic disorder of middle-aged adults that always appears on UV-exposed skin. It is a form of granulomatous dermatosis characterised by annular plaques with central atrophy and raised erythematous margins that are similar to those observed in granuloma annulare. 

There is debate around whether actinic granuloma is a variant of annular elastolytic giant cell granuloma that only affects the face, or a different entity. 

• Although the pathogenesis is unknown, the most accepted theory is that it is a granulomatous reaction induced by an antigenic agent present in the elastic fibres affected by the sun exposition

• Predominantly affects middle-aged individuals and has a female predilection

• Actinic granuloma presents with small papules that quickly evolve into annular plaques with a gradually expanding border. The centre has a pale atrophic appearance

• The lesions are histopathologically similar to granuloma annulare and show non-palisading granulomas with foreign-body-type, multinucleated giant cells as well as lymphocytes and histiocytes. The lymphocytes are predominantly CD4 positive. The histopathologic criteria that distinguish actinic granuloma from granuloma annulare are the absence of elastic fibres in the centre of the actinic granuloma lesions and the presence of elastic fibres within giant cells. Additionally, there should not be any increase in mucin, which might be expected in granuloma annulare

• UV-protection aims to reduce the development of further lesions
• There is no reliably effective treatment. Infiltration of corticosteroids into the raised edge, phototherapy, and antimalarials antimalarials are largely ineffective
• Some patients experience spontaneous resolution