To identify clinical features associated with response to tonsillectomy among children with periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome and to determine optimal management of children with continued episodes after tonsillectomy.

Patients with PFAPA seen at Vanderbilt University Children's Hospital and the National Institutes of Health (NIH) who underwent tonsillectomy were enrolled and queried regarding symptoms before and after surgery.

Ninety-seven subjects with PFAPA (43 Vanderbilt, 54 NIH) were followed for a median of 49 months following tonsillectomy. Nearly half of participants reported complete resolution of PFAPA episodes (65% at Vanderbilt and 35% at NIH), while 25% had less severe or frequent episodes, 23% had a period of remission with recurrence, and 4% had no change in episodes. By logistic regression, factors associated with a full response to tonsillectomy were episode resolution with glucocorticoid treatment, presence of exudative pharyngitis, absence of rash, and absence of arthralgia/myalgia during pre-tonsillectomy PFAPA flares. Among those requiring treatment for persistent flares post-tonsillectomy, 15/19 (79%) reported improvement with cimetidine or famotidine prophylaxis.

Tonsillectomy remains effective in improving PFAPA flares in most patients. However, unique episode features prior to tonsillectomy appear to be clinical predictors of response to tonsillectomy. Histamine receptor 2 antagonists like cimetidine were effective prophylactic agents for refractory cases post-tonsillectomy. Patients with incomplete response to tonsillectomy may represent a subset of PFAPA with unique factors affecting their pathogenesis.