Acute sinusitis mimicking antrochoanal polyp.

Three cases of antral sinusitis that presented in an unusual fashion are reported. In each case, the inflamed, swollen sinus mucosa became redundant and prolapsed into the nasal cavity through a widened sinus ostium, mimicking the findings of an antrochoanal polyp. The cases represent the first report in the radiographic literature of this unusual manifestation of maxillary sinusitis.