Herniation of the antral membrane through an extraction site. Report of a case. A case of herniation of the antral membrane through a recent extraction site is presented. The lesion was initially diagnosed as a tumor by the referring dentist. Oroantral fistulas are not an uncommon finding after dental extractions. It is rare, however, to see herniation of the antral membrane with large polyps extending through the fistula into the oral cavity. A search of the literature revealed only two other such cases. Surgical removal of the polyps and closure of the oroantral fistula by means of a buccal sliding flap technique is discussed. 