Musculoskeletal and Skin Pathology for Medical II Students

Lab 1e Osteosarcoma (11000-91803)

Osteosarcoma (osteogenic sarcoma) is the most common primary malignant tumor of bone. It is a neoplasm of mesenchymal cells in which the tumor cells produce osteoid or bone. Most osteosarcomas are primary (no underlying bone disease) and arise in the second decade of life. The most common sites for primary osteogenic sarcoma are in the lower end of the femur and the upper end of the tibia (around the knee joint). Secondary osteosarcoma develops in a patient with a preexisting bone disease, most often Paget's disease of bone, multiple osteochondromas, enchondromas or after irradiation. The slide in your class set is from a conventional or medullary osteogenic sarcoma. There exist other variants of osteosarcoma, such as parosteal osteosarcoma, that have a different histologic appearance and prognosis. As with all bony lesions, it is essential to correlate the gross and histopathologic features with the history and physical findings, and radiographic appearance.

Slides 8 & 9 | Slides 10 & 11

Slide 8 A fresh specimen and shows an osteolytic tumor in the medullary cavity of the diaphysis of the proximal end of the humerus. The tumor does not appear to have penetrated the epiphyseal plate. There is a large soft tissue component of this tumor.
Slide 9 A fixed specimen of an osteogenic sarcoma of the tibia, with penetration of the cortex and elevation of the periosteum by the tumor with several layers of new bone. This forms "Codman's triangle", a sign of advanced disease which can be seen radiographically in some cases of osteogenic sarcoma.

Digital Legends for Labs/Cases
Lab 1
1a | 1b | 1c | 1d | 1e | 1f | 1g
Gross & Radiographs
a | b | c | d | e | f | g | h 
Lab 2
2a | 2b | 2c | 2d | 2e | 2f

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Medical II

Updated August 28, 2007