Respiratory Epithelial Adenomatoid Hamartoma: An Important Differential of Sinonasal Masses

: Background Respiratory epithelial adenomatoid hamartomas (REAH) are rare, glandular proliferations of the aerodigestive tract lined by ciliated respiratory epithelium. We report nine cases of REAH and devised a histopathological guide to differentiate these lesions from its main differentials. Methods Patients with biopsy-proven REAH were included in the series. Lesions were removed endoscopically and sent for histopathological analysis. The macroscopic and microscopic features were reviewed. Results Nine patients (age 59 ± 15.5 years, 78% male) with REAH were analysed. Findings revealed glandular proliferations lined by ciliated respiratory epithelium without metaplastic changes and intervening oedematous stroma. This is in contrast to a typically thickened epithelial basement membrane with oedematous stroma seen in nasal polyps. Conclusion REAHs are benign entities that should be included in the differential diagnosis for sinonasal masses. Prompt detection by tissue biopsy is crucial to differentiate these lesions from nasal polyps and more aggressive pathologies and avoid unnecessary surgery.