Incidence and grading of cranio-facial osteosarcomas.

Osteosarcoma of the cranio-facial structures and skull is rare. In children, only 5.6% of cases are localized in these areas. It is claimed that the mean age at presentation is at least 10-15 years higher than for osteosarcomas in other parts of the body. However these reports are based on data from single institutions or compiled from several registries. It is further claimed that tumours in the mandible and maxilla are less malignant, as based on observations of a better prognosis and lower incidence of metastatic spread as compared with osteosarcomas arising elsewhere. We report all histologically proven cranio-facial osteosarcomas in The Netherlands occurring over a 20-year period, based on the national registration covering all Dutch pathology laboratories (PALGA). The age-corrected incidence of primary osteosarcoma ranged from 0.33 to 0.41 per million across the age ranges. The mandible was the most frequent site of involvement. Only 61% had a high malignant histological grading. Our data indicate that the age-corrected incidence of primary osteosarcomas is similar across all age ranges. In respect to histology, a lower grade of malignancy is more frequent. Maxillary lesions significantly more often have a lower histological grade of malignancy.