Poline J, Fogel O, Pajot C, et al. - In this retrospective, multicentre observational cohort study involving 21 patients diagnosed with genetically confirmed Blau syndrome (BS; a rare monogenic autoinflammatory disease caused by NOD2 mutations), researchers sought to provide a detailed clinical and microscopic analysis of skin manifestations and to ascertain if they can contribute to an early diagnosis. In the large majority of patients, skin involvement in BS is the earliest clinical manifestation of the BS. Key to early diagnosis of BS is the recognition of dermatological manifestations as granulomatous skin lesions and early dermatological expertise. In view of the findings, proposing a simplified view of BS skin lesions in which the granuloma is the primary structure seems rational.