Repeated dedifferentiation of low-grade intraosseous osteosarcoma

Low-grade intraosseous osteosarcoma is an uncommon bone tumor that is chara cterized by minimum cytological atypism and a much better prognosis than co nventional osteosarcoma. This report describes a patient who had a low-grad e osteosarcoma that mimicked fibrous dysplasia (FD). The tumor had an area of high-grade sarcoma at the initial diagnosis. Ten years after incomplete resection of FD-like tumor, local recurrence with areas of high-grade tumor developed. This case illustrates the potential of dedifferentiation in low -grade intraosseous osteosarcoma. Copyright (C) 2000 by W.B. Saunders Compa ny.