Classification and behaviour after surgery of canine 'epulides'.

Seventy-five surgically excised canine gum neoplasms, which had previously been diagnosed as epulis or ameloblastoma, were reclassified on the basis of their presumed tissue of origin. They included 42 tumours of fibroblastic origin, which contained small foci of odontogenic epithelium and were classified as peripheral odontogenic fibroma, whilst 31 epithelial tumours were classified as basal cell carcinomas arising from the gum epithelium. Two epithelial tumours which apparently arose within the bone of the mandible and were not connected with the surface mucosa were classified as ameloblastomas. Follow-up studies after surgery revealed a recurrence rate of 17 per cent for the odontogenic fibromas and 50 per cent for basal cell carcinomas. Neither of the ameloblastomas, which were initially treated by radical excision, recurred locally and no metastases were detected from any of these tumours.