Granulomatous cutaneous sarcoidosis: diagnosis, relationship to systemic disease, prognosis and treatment

Sarcoidosis is an antigen-mediated disease of unknown aetiology, characterized by the presence of non-caseating epithelioid cell granulomas in multiple organs. Cutaneous involvement in sarcoidosis is classified as specific, when biopsy reveals non-caseating granulomas, and non-specific, typically erythema nodosum. Granulomatous skin lesions occur in 9% to 37% of patients. The skin is the second most commonly involved organ after the lung. A skin biopsy is easy to perform and enables an early diagnosis with a minor invasive procedure. Some types of specific lesions have prognostic significance and may help to predict the outcome of the systemic disease. Maculopapules, subcutaneous nodules and scar sarcoidosis are usually transient or tend to follow the course of the systemic disease. Skin plaques and lupus pernio are associated with chronic sarcoidosis. Although most cutaneous lesions of sarcoidosis do not cause significant morbidity and do not require treatment, some have cosmetic importance because they may be disfiguring and can have a strong psychosocial impact. Treatment of these lesions is a challenge since they do not respond well to conventional treatments. This manuscript reviews the clinical characteristics of the more frequent types of specific cutaneous lesions of sarcoidosis, the relationship between cutaneous involvement and systemic disease, the prognostic significance of lesions and the present state of treatment of difficult cases of cutaneous sarcoidosis.