Dedifferentiated chondrosarcoma, light micrograph. These tumours show a combination of low-grade chondrosarcoma (less cellular bluish-pink areas) admixed with a high-grade sarcomatous component (more cellular, darker purple-pink areas at top and bottom). Usually, there is a sharp transition between the low-grade and high-grade components, as seen here. Chondrosarcoma is a malignant tumour which shows chondroid (cartilaginous) differentiation. It is a tumour of adulthood and old age, most commonly presenting in 4th to 6th decades of life. The most common locations are the pelvic bones, ribs, shoulder girdle and the femur (thigh bone). Haematoxylin and eosin stain.