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Presented by Edward McCarthy, M.D. and prepared by Greg Seidel, M.D.
Case 1: A 16 year old girl had pain and swelling of her mid tibia for one year.
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Question 1 of 1
1. Question
Week 96: Case 1
A 16 year old girl had pain and swelling of her mid tibia for one year. A radiograph showed a surface radiodensity composed of rings and stippled calcifications./images/0729021a.jpg
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/images/0729021e.jpgCorrect
Answer: Periosteal osteosarcoma
Histology: Periosteal osteosarcoma is a surface osteosarcoma that has predominantly chondroblastic differentiation. In fact, the cartilage may be so extensive that the osteoid is extremely difficult to find. Cases are frequently misdiagnosed as chondrosarcoma. Periosteal osteosarcoma is an intermediate grade sarcoma. The cartilage shows mild atypia. Characteristically, peripheral margins of each cartilage lobule is a condensation of chondrocytes into a more cellular area. It is usually in this area that neoplastic osteoid seams are found, a feature which mandates the diagnosis of osteosarcoma. Atypia of the stromal cells surrounding the osteoid seams is minimal.
Discussion: The lesion is not a surface chondrosarcoma because of the neoplastic osteoid that is present. This means that the tumor cells themselves are synthesizing the osteoid. This automatically renders a diagnosis of osteosarcoma. The characteristic condensation of cells at the rim of the lobules of cartilage is characteristic of chondoblastic osteosarcoma and is not seen in conventional chondrosarcoma.
The lesion is not a periosteal chondroma. There is too much cellular atypia and neoplastic osteoid. Also the lesion is extensively encircling the shaft of the tibia. Periosteal chondroma is a well-defined lesion.
The lesion is not an osteochondroma because there is no bony stalk and the cartilage is atypical with neoplastic osteoid production.
Incorrect
Answer: Periosteal osteosarcoma
Histology: Periosteal osteosarcoma is a surface osteosarcoma that has predominantly chondroblastic differentiation. In fact, the cartilage may be so extensive that the osteoid is extremely difficult to find. Cases are frequently misdiagnosed as chondrosarcoma. Periosteal osteosarcoma is an intermediate grade sarcoma. The cartilage shows mild atypia. Characteristically, peripheral margins of each cartilage lobule is a condensation of chondrocytes into a more cellular area. It is usually in this area that neoplastic osteoid seams are found, a feature which mandates the diagnosis of osteosarcoma. Atypia of the stromal cells surrounding the osteoid seams is minimal.
Discussion: The lesion is not a surface chondrosarcoma because of the neoplastic osteoid that is present. This means that the tumor cells themselves are synthesizing the osteoid. This automatically renders a diagnosis of osteosarcoma. The characteristic condensation of cells at the rim of the lobules of cartilage is characteristic of chondoblastic osteosarcoma and is not seen in conventional chondrosarcoma.
The lesion is not a periosteal chondroma. There is too much cellular atypia and neoplastic osteoid. Also the lesion is extensively encircling the shaft of the tibia. Periosteal chondroma is a well-defined lesion.
The lesion is not an osteochondroma because there is no bony stalk and the cartilage is atypical with neoplastic osteoid production.
