Primary osteosarcoma of the uterine corpus. Report of a case and critical review of the literature.

Uterine osteosarcoma represents an extremely rare pure heterologous sarcoma of the uterus. In the present case osteosarcoma occurred primarily in the uterine cavity of a 56-year-old woman. The tumor was anaplastic and the presence of different proliferative patterns caused differential diagnostic problems with various malignant tumor types. The osteoid features of extracellular matrix were demonstrated by electron microscopy. Clinical and pathological features of previously reported cases of uterine osteosarcoma are critically reviewed.