Surgical outcomes and unique histological features of tonsils after tonsillectomy in adults with periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis syndrome

Objectives: Data on the adult-onset periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome are scarce. European studies reported that unlike pediatric-onset PFAPA, tonsillectomy is ineffective for adult-onset PFAPA. The aims of this study were (1) to assess the response to tonsillectomy in a cohort of Japanese adult-onset PFAPA patients and (2) to evaluate the histologic appearance of tonsils in adult-onset PFAPA patients and to compare them with those of tonsils from age- and sex-matched controls with chronic tonsillitis. Methods: In this retrospective cohort study, 5 adults with PFAPA and 15 controls who had undergone tonsillectomy were recruited. The size of the tonsil germinal centers was measured by hematoxylin and eosin staining, and the number and density of B and T lymphocytes in germinal centers were measured by immunohistochemistry, using CD3, CD4 and CD8 as T cell markers and CD20 as B cell marker. Results: All patients had complete remission of the symptoms after surgery. PFAPA patients had significantly smaller germinal center areas than controls. The number and density of CD8+ cells in germinal centers were significantly lower in tonsils from PFAPA compared with controls. No differences were found between the two groups in CD3+, CD4+, and CD20+ cells. These results are compatible with the tonsillar features of pediatric-onset PFAPA. Conclusion: Our report demonstrates that tonsillectomy might be effective for adult-onset PFAPA and that tonsils of adult- and pediatric-onset PFAPA share the same histological features. These results suggest that the pathogenic mechanisms of adult- and pediatric-onset PFAPA are identical.