骨肉瘤由梭形细胞组成。粉红色的类骨质显示一定的分化程度，提示骨肉瘤。
The osteosarcoma is composed of spindle cells. The pink osteoid formation seen here is consistent with differentiation that suggests osteosarcoma.
This large mass lesion is a liposarcoma. Common sites are the retroperitoneum and thigh, and they occur in middle aged to older adults. This one is yellowish, like adipose tissue, and is well-differentiated. Though indolent, it continues growing to reach a large size, and following excision, it has a tendency to recur.