Multifocal osteosarcoma in childhood.

Osteosarcoma is one of the most common primary malignant bone tumours in childhood, mainly affecting the metaphysis of long extremity bones. In rare cases, patients present at time of diagnosis with multiple bone lesions, sometimes in the absence of pulmonary metastases. The pathology pattern of these multifocal osteosarcomas occurring with a rare incidence of 0.5-4% is not yet clear, and in spite of investigations in diagnosis and therapy, the prognosis is still poor. We report two cases of multifocal synchronous osteosarcoma. The age of both children at the time of tumour detection was 14 years. A synchronous or metachronous occurrence of multiple bone lesions, initially in the absence of pulmonary metastases was seen. In both cases, treatment consisted of neoadjuvant chemotherapy, oncologic surgery and adjuvant chemotherapy. Tumour response to chemotherapy was good in one patient, and poor in the other case. In both patients initial R0-resection of the tumours was performed. The disease-free time was 1 year before detection of pulmonary metastases or relapse. By the combination of chemotherapy and aggressive surgery the prognosis in multifocal osteosarcoma has been improved over the last years. Nevertheless, the survival time is still short and seems to be correlated with the initial histological tumour response to chemotherapy.