62.OSTEOID OSTEOMA ARISES FROM
A.PERIOSTEUM
B.CORTEX
C.MEDULLARY CAVITY
D.ALL OF THE ABOVE
ANS:ALL OF THE ABOVE
Three types of osteoid osteomas have been described by Edeiken:
Cortical/classic: The most common type, seen in 75% of cases. A lucent lesion, the nidus, is located in the center of reactive sclerosis and periosteal reaction. The periosteal reaction is usually solid, but may be lamellated. Tends to affect the tibia and femur.
Cancellous/medullary : About 25% of cases. Tends to affect the femoral neck, small bones of the hands and feet, and the spine. Sclerosis, if present, is mild or moderate. The lucent nidus is not necessarily in the center of the sclerosis, which may be located some distance away. In the spine, the differential diagnosis would include osteoblastoma.
Subperiosteal: The rarest type. Presents as soft tissue mass adjacent to bone, which may demonstrate pressure erosion or resorption, but little or no significant reactive sclerosis. Tends to affect the medial aspect of the femoral neck, the hands and feet, and the talar neck. Patients with a painful joint may initially be evaluated with ultrasound, and the finding of cortical irregularity and focal synovitis should raise the possibility of an intraarticular osteoid osteoma.
A.PERIOSTEUM
B.CORTEX
C.MEDULLARY CAVITY
D.ALL OF THE ABOVE
ANS:ALL OF THE ABOVE
Three types of osteoid osteomas have been described by Edeiken:
Cortical/classic: The most common type, seen in 75% of cases. A lucent lesion, the nidus, is located in the center of reactive sclerosis and periosteal reaction. The periosteal reaction is usually solid, but may be lamellated. Tends to affect the tibia and femur.
Cancellous/medullary : About 25% of cases. Tends to affect the femoral neck, small bones of the hands and feet, and the spine. Sclerosis, if present, is mild or moderate. The lucent nidus is not necessarily in the center of the sclerosis, which may be located some distance away. In the spine, the differential diagnosis would include osteoblastoma.
Subperiosteal: The rarest type. Presents as soft tissue mass adjacent to bone, which may demonstrate pressure erosion or resorption, but little or no significant reactive sclerosis. Tends to affect the medial aspect of the femoral neck, the hands and feet, and the talar neck. Patients with a painful joint may initially be evaluated with ultrasound, and the finding of cortical irregularity and focal synovitis should raise the possibility of an intraarticular osteoid osteoma.
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