1. A case of osteoid osteoma which recurred twice after block excision is reported. 2. It is postulated that recurrence is almost certainly caused by incomplete removal of the nidus, either by curettage or by incomplete block excision. 3. Why curettage is successful in most cases but not in others is obscure, but it may be that the arterial supply to the tumour is interrupted. 4. Block excision with adequate radiographic control to ensure its completeness is the treatment of choice.
Two cases of malignant angioblastoma of tibia are described, one finally treated by amputation and the other by segmental resection and grafting. They have remained free from signs of local recurrence or distant metastasis for five and a half and ten and a half years respectively. Both showed prominent areas of neoplastic mesenchymal angioblastic tissue which closely imitates solitary fibrous dysplasia. The natural history and radiological characteristics of these little-known tumours, long thought to be "adamantinoma" of bone, are described.
