BackgroundAdenoid hypertrophy is a common cause of upper airway obstruction, and adenoidectomy is one of the most frequently performed operations in children. Topical nasal steroids can act directly on nasopharyngeal lymphoid tissue to decrease its reactive inflammatory changes and potentially reduce its size.ObjectiveTo study the light microscopic changes in adenoidal lymphoid tissue after one month of topical steroid use.MethodsTwenty-six children with adenoid hypertrophy grade 3 scheduled for adenoidectomy were randomly divided into two equal groups: one group received mometasone furoate aqueous nasal spray (Nasonex) 100 mcg/day for four weeks, and a control group received nasal normal saline 0.9 per cent for four weeks. The removed adenoids were examined histopathologically.ResultsAdenoidal tissue from the mometasone group had less reactive germinal centres and less spongiosis compared to the control group. The latter showed proliferating, reactive, variable sized and shaped lymphoid follicles, with congested blood vessels in the interfollicular areas.ConclusionThe use of intranasal mometasone furoate aqueous nasal spray (Nasonex) for one month reduced adenoidal tissue reactive cellular changes and its vascularity. This is, however, a pilot study; a longer treatment period is needed to assess the effect of treatment on adenoidal size.