Case report: periosteal osteosarcoma of the clavicle.

Periosteal osteosarcomas are rare and usually affect the meta-diaphyseal region of long bones. We present a case of a periosteal osteosarcoma of the clavicle, a highly unusual site and representing one of only two such cases documented in the English literature. This case illustrates the diagnostic dilemmas in the classification of such tumors, particularly in small biopsy specimens from unusual locations. It emphasizes the importance of radiological and pathological correlation.