A previously healthy 41-year-old man presented with a 5-day history of fever, arthritis, and cutaneous lesions. The patient denied any treatment, did not use alcohol or illicit drug. On physical examination he was healthy and febrile (38.1°C). An inflammatory monoarthritis of the right ankle was obvious making walking impossible (Fig. 1a). A dozen of maculopapular and pusutlar lesions were present on the forearms and lower limbs (Fig. 1b). Physical examination was otherwise unremarkable. The white blood cell count showed leukocytosis of 9760 neutrophils/mm3 with 80% neutrophils and 13% lymphocytes, normal serum creatinine and urinalysis, and liver function tests, CRP level was 311mg/l.