Squamous odontogenic tumour: review of the literature and a new case.

Squamous odontogenic tumour (SOT) is a rare benign odontogenic neoplasm, apparently arising from rests of Malassez. It was first described in 1975 and since then only 17 cases have been recorded in the literature. A new, not previously reported, characteristic case of SOT is presented in connection with a review of the literature. It is concluded that the lesion occurs with equal frequency in the maxilla and mandible and now and then multifocally. Maxillary lesions seem to grow more aggressively than do mandibular ones. The symptoms are modest. SOT has a characteristic pathologic picture which differs decisively from ameloblastoma and which, in connection with its benign nature, warrants the classification of SOT. Although most cases have been treated by conservative surgical therapy without recurrence, there are cases, especially in the maxilla with diffuse lesions, which have required en bloc resection or hemimaxillectomy. The diagnostic problems are stressed and recommendations are made for the pathologist and the surgeon to pay attention to this rare but benign tumour.