A 45-year-old man has experienced pain in the area of the left hip and upper thigh for the past 7 months. On physical examination, there is tenderness on deep palpation of the left side of the groin. There is a reduction in range ofmotion at the left hip. There is no swelling or warmth to the touch. Pelvic and left leg radiographs show an upper femoral masslesion arising in the metaphyseal region and eroding the surrounding bone cortex. The proximal femur is excised and on sectioning has the gross appearance shown in the figure. Which of the following cell types is most likely to be proliferating in this mass?
Primitive neuroectodermal cells
Answer :B Chondroblasts
The glistening, gray-blue appearance shown in the figure is typical of cartilage, and this lesion most likely represents neoplastic proliferation of chondroblasts.
The tumor has infiltrated the medullary cavity and invaded the overlying cortex, and is malignant. This is a chondrosarcoma. Most chondrosarcomas are low grade.
They occur in a broad age range, in contrast to many other bone tumors that tend to occur in children or in young adults. Most chondrosarcomas arise toward central portions of the skeleton. Osteosarcomas are derived from osteoblasts.
They are usually seen in younger individuals and do not have a bluish-white appearance because they are marked by osteoid production.
Giant-cell tumors arise during the third to fifth decades; they involve epiphyses and metaphyses.
Grossly, they are large, red-brown, cystic tumors. Giant-cells resembling osteoclasts are present in giant-cell tumors of bone. These tumors are believed to arise from cells of monocyte-macrophage lineage.
Primitive neuroectodermal cells are present in Ewing sarcoma.