Low grade central osteosarcoma--a diagnostic dilemma.

Low grade central osteosarcoma is a rare primary bone tumor. This fibro-osseous lesion shares some radiological and histopathological resemblance with fibrous dysplasia, which is a more common entity. Thus it may be mistaken as fibrous dysplasia and may receive inadequate treatment resulting in a more malignant recurrent bone tumor. We present a case of low grade central osteosarcoma of the right tibia, which was initially treated as fibrous dysplasia with curettage and bone grafting. Three years later the tumor recurred with greater soft tissue and bony involvement but without metastasis. The patient was treated with above knee amputation and has been asymptomatic for the last two years.