<s>[INST] <<SYS>> This is a medical question of type : causes <</SYS>> What causes Periodic fever, aphthous stomatitis, pharyngitis and adenitis ? [/INST] What causes periodic fever, aphthous stomatitis, pharyngitis, cervical adenitis (PFAPA)? The cause of PFAPA is unknown, although viral or autoimmune causes have been suggested. </s>