The hyperimmunoglobulinaemia D (IgD) syndrome (HIDS) is a recently described periodic disease, manifested by febrile episodes, lasting several days and accompanied by abdominal pain, symmetrical oligoarthritis, cervical lymphadenopathy, skin lesions, and constantly increased serum IgD concentrations (>100 units/ml).1 HIDS shares its episodic febrile nature and many painful manifestations with several other clinical conditions, including familial Mediterranean fever, familial Hibernian fever, and Behçet’s disease (BD). Indeed, in a leading textbook of rheumatology, these entities were recently grouped in one chapter, entitled Intermittent and Periodic Arthritic Syndromes.2 Manifestations, distinguishing …