Discuss chondrosarcoma: who gets it, how does it present, and how does it appear grossly and microscopically. (<250 words)

Chondrosarcoma is the second most common primary bone cancer, excluding hematopoietic malignancies such as multiple myeloma, and it occurs more often in males than females. There is a wide age distribution, with many of these tumors appearing in middle to later life. About three-fourths of chondrosarcomas are primary, without a pre-existing lesion, while the rest are secondary, arising in a benign cartilagenous tumor such as an enchondroma or a chondroblastoma. Most arise in the metaphyseal region of bones of the central axial skeleton and about the knee. Patients may present with local pain, though sometimes a firm mass lesion can be palpated. Grossly, chondrosarcomas consist of bulky masses of bluish to grey-white translucent tissue. Calcifications may be present, and central necrosis can produce a lytic area. These tumors are usually slow-growing but eventually erode the bone cortex and extend into the surrounding soft tissue. Microscopically, there is chondroid matrix without osteoid. The degree of anaplasia in chondrocytes helps to distinguish low-grade, less aggressive tumors from the less common high-grade chondrosarcomas.