“Periodic fever, aphthous stomatitis, pharyngitis and adenitis syndrome is a medical condition, typically starting in young children, in which high fever occurs periodically at intervals of about 3–5 weeks, frequently accompanied by aphthous-like ulcers, pharyngitis and/or cervical adenitis (cervical lymphadenopathy). The syndrome was described in 1987 and named two years later.”
PFAPA is the most common periodic fever syndrome in children, but its cause(s) and its pathogenesis are currently unknown. Suggested possible causes include problematic genetics and/or effects of previous infection.
Research from 2020 suggests that two other diseases, aphthous stomatitis and Behçet’s disease may be on a 'common spectrum' along with PFAPA - and could be different manifestations of the same 'spectrum disorder'.