Respiratory epithelial adenomatoid hamartomas of the olfactory clefts.

The objective of this study is to report a 5-year experience with Respiratory Epithelial Adenomatoid Hamartoma (REAH) of the olfactory clefts. The study design is retrospective observational study and the setting is in a Tertiary medical center. The charts of all adult patients operated on bilateral nasal polyps between 2003 and 2008 were retrospectively checked up on the diagnosis of REAH. Three periods have been distinguished according to our experience with REAH. REAH can be observed either as bilateral pseudotumours confined to the olfactory clefts (n = 12 between 2003 and 2008) or associated to nasal polyposis of the ethmoid labyrinths. As the diagnosis of associated REAH became more evident, the number of recognized cases increased from 0% in 2003 and 2004 to 1.6% in 2005 (1/64 patients) and 12.5% in 2006 (10/80 patients) (period 1). Systematic endoscopy of the olfactory clefts during ethmoid labyrinth surgery increased the proportion to 27% (27/100 patients) (period 2). Systematic biopsies of abnormal mucosa in the olfactory clefts during ethmoid surgery increased the proportion to 48% (31/65 patients). The histopathological diagnosis of REAH has been described in 1995 and added to the World Health Organization classification of tumours in 2005. Pseudotumoural REAH confined to the olfactory clefts represent a differential diagnosis for bilateral naso-ethmoidal polyposis. The significance of REAH associated to naso-ethmoidal polyposis is unclear.