Intraosseous verrucous carcinoma (IOVC) arising from an odontogenic cyst is extremely rare. We report a case of intraosseous verrucous carcinoma in a 74-year-old male who presented with a left mandibular swelling with recurrent pus discharge from gingiva of tooth #35. Panoramic radiography revealed an impacted tooth #34 and a large well-defined, radiolucent lesion surrounding the crown of tooth #34. The clinical diagnosis was an infected dentigerous cyst. Surgical excision of the cyst together with extraction of tooth #34 was performed. Histopathological examination showed proliferation of hyperparakeratotic stratified squamous cyst lining epithelium and down-growth of broad and bulbous epithelial ridges with pushing border invasion into the fibrous cystic wall. A verrucous carcinoma arising from an infected dentigerous cyst was diagnosed. There was no recurrence of the tumor 5 months after surgery.
