Clinical and Molecular Presentation of Respiratory Epithelial Adenomatoid Hamartoma: A Systematic Review

BackgroundRespiratory epithelial adenomatoid hamartoma (REAH) is a benign tumor-like lesion that appears in the sinonasal tract. Due to the lack of well-defined distinctive features of REAH, specifically clinical and molecular characteristics, this lesion is often misdiagnosed as an inflammatory nasal polyp or sinonasal malignancy.ObjectiveThis study aimed to systematically review the existing literature to determine the distinguishing attributes of REAH.MethodsIn accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a Medline, EMBASE and Web-of-Science literature review was undertaken to evaluate studies published till July 1, 2024. Forest and funnel plots were used to present prevalence and potential small-study effects, respectively. The estimates were calculated using random-effects methodology. The I² value was determined to assess the interstudy heterogeneity. The quality of the included studies was evaluated using National Heart, Lung, and Blood Institute Study Quality Assessment Tools.ResultsA total of 39 studies were included, of which 10 investigated molecular characteristics. Several studies have shown the involvement of inflammatory processes in REAH. In addition, 37 studies with 1127 patients met the inclusion criteria for the meta-analysis. The findings of these studies showed that REAH was most commonly identified in the olfactory cleft (66.7% [49.8%-83.7%]), often bilaterally (66.4% [54.0%-78.7%]). Furthermore, REAH was associated with enlarged olfactory cleft widths on computed tomography scans, with an estimated width of 10.58 mm [9.41-11.75 mm].ConclusionOur study showed that inflammatory responses likely play a role in REAH. Notably, the symptoms of REAH are often indistinguishable from those of chronic rhinosinusitis with nasal polyposis. Thus, a high index of suspicion is required to diagnose REAH, typically when patients present with bilateral olfactory cleft masses with an enlarged olfactory cleft width on a computed tomography head scan.