Blau syndrome is a rare genetic disease affecting skin, eyes, and joints. In skin, it manifests as granulomatous dermatitis. The lesions are hard, persistent nodules. Other clinical features include arthritis and uveitis. Reference: https://medlineplus.gov/genetics/condition/blau-syndrome/#:~:text=Blau%20syndrome%20is%20an%20inflammatory,earliest%20sign%20of%20Blau%20syndrome. Image via: https://www.medicalnewstoday.com/articles/blau-syndrome