title: Can an osteoblastoma become malignant?
abstract: A rare case of an osteoblastoma in the clavicle is reported, that became malignant within 3 1/2 years, after two recurrences. The clinical course of the disease and a comparison of tissue sections removed during a total of four operations point to a secondary malignant transformation of an osteoblastoma, such as has been described by Schajowicz, among others. Six years after the first diagnosis was reached and 3 1/2 years after the last resection of the clavicle and the removal of a tumour from definitely healthy surrounding tissue, and after long-term chemotherapy, the now 17-year-old youth is free of metastases and there is no sign of a recurrence of the tumour. The problem of differentiating this kind of tumour from other types is discussed in light of international literature on the subject, and therapeutic recommendations are made.
mesh_terms: D001859:Bone Neoplasms / Q000473:pathology*; D002648:Child; D002968:Clavicle; D006801:Humans; D008297:Male; D010017:Osteoma, Osteoid / Q000473:pathology*