A previously healthy 12-year-old boy, with no relevant family history, presented to the dermatology outpatient clinics with ulcers with well-defined border, nodules and erythematousviolaceous plaques, on his left leg (Fig. 1), with an intermittent evolution over the last 4 years. Two years after the appearance of skin lesions, he also had sporadic abdominal pain, oral aphthae, every 2 months, and elbow and right knee pain, without heat, redness, loss of function or joint swelling. No fever, blood or mucus in stool. Analytic tests revealed an elevated erythrocyte sedimentation rate of 54 mm/h (normal range 0-19 mm/h), a C-reactive protein of 18.05 mg/L (normal range 0-5 mg/L) and elevated faecal calprotectin, 1690 μg/g (normal range < 50 μg/g). Viral serologies and Interferon Gamma Release Assay tests were negative.