[Atypical sarcoidosis].

PURPOSE: Sarcoidosis is a granulomatous disease of unknown etiology. Lung and lymphatic system are the principal localisations. Clinical presentations are various depending on involved organs. Some presentations, which are easily diagnosed, are typical and frequent. Atypical forms have unusual presentations and/or are rare. Beside, in a multisystemic sarcoidosis, the affection of only one organ can be unusual. Rigorous diagnosis procedure could avoid errors. CURRENT KNOWLEDGE AND KEY POINTS: Twenty percent of sarcoidosis have atypical presentation. However, each of them are infrequent. Atypical features are wide and can concern pulmonary or extrapulmonary manifestations, general manifestations, blood testing or pathological pattern. FUTURE PROSPECTS AND PROJECTS: Describing atypical forms are necessary for their diagnosis. The diagnosis of atypical sarcoidosis is found on the knowledge of atypical forms previously described, presence of granulomas on specimen biopsy and excluding other granulomatous disease.