Ossifying Epulis in a Thoroughbred Foal

A 4-month-old female thoroughbred foal was presented with large mass on mandibular gingiva. The enlarged mass was firm and yellowish pink in color, and occupied the whole mandibular arcade. The filly could not close her mouth with her lips. Radiographs showed radioopaque mass under the mandible. The mass was surgically excised from mandible. Histopathologically, gingival mass was characterized by hyperplastic gingival epithelium, well vascularized collagenous stroma and large area of bony tissues. Based on the gross and histopathologic findings, this case was diagnosed as ossifying epulis in the mandibular gingiva. This is the first report of ossifying epulis in a thoroughbred horse in Korea.