Review Question - QID 7519

The most likely diagnosis is osteoblastoma, which has a widely varied radiographic appearance. It can often best be described as a large osteoid osteoma (> 1 to 2 cm). It can be lytic or blastic, but is usually well-marginated, indicating its benign nature. Histology shows trabecula with intermixed nonmalignant osteoblasts. Osteoid osteoma is a small (< 1 to 2 cm) lesion with thick sclerotic bone surrounding a small lytic nidus. Histology is very similar to osteoblastoma. Osteosarcoma has malignant cells seen on histology. Nonossifying fibroma is an eccentric lytic lesion occurring in the metaphysis and has a bland fibrous background arranged in a storiform pattern with scattered giant cells under the microscope. Osteomyelitis tends to be partially lytic often with a draining sinus or overlying skin changes. Fibrous dysplasia is characterized by ground glass calcification and a chinese character pattern on histology.