Sarcoidosis.

Sarcoidosis is a systemic granulomatosis characterized by the formation of epithelioid and giant cell granulomas without caseous necrosis. To make the diagnosis, it is necessary to prove systemic granulomatosis involving at least two organs; but in practice, a combination of clinical, paraclinical and histologic findings is used. It affects predominantly women with a bimodal age distribution: 25-29 years and 65-69 years. The most commonly affected organs are the mediastinal lymphatic system, lungs, skin and eyes. Ophthalmological involvement is present in 20 to 50% of cases. The typical ocular presentation is that of granulomatous uveitis associated with venous retinal vasculitis and lesions of peripheral multifocal choroiditis. This ophthalmological presentation, although very evocative, is not always associated with systemic disease. The diagnosis of ocular sarcoidosis is then presumed in the absence of histological evidence. Algorithms combining ophthalmological and systemic signs have been proposed in cases of isolated uveitis. They make it possible to establish the diagnosis of ocular sarcoidosis with various levels of probability. The absence of significant granulomas on a systemic level during primary ocular involvement remains the main hypothesis to explain these diagnostic difficulties. Treatment is well described, as the uveitis of sarcoidosis is most often steroid responsive. In the case of corticosteroid-dependent uveitis, the first-line immunosuppressant remains methotrexate. The use of anti-tumor necrosis factor alpha is an interesting alternative in patients whose ocular sarcoidosis is refractory to conventional immunosuppressants.