Multiple lamellar hypodense foci in bone is a description of the site of the lesion on imaging such as CT or X-ray. That is, the presence of multiple lesions in the bone is examined. The common causes of flaky low density foci in bone are bone cysts, bone inflammation or osteonecrosis. 1. Bone cyst: It is a cyst-like limited lesion in the bone, which is a benign bone tumor-like lesion. There are usually no obvious symptoms, or localized soreness, vague pain, mild pressure and other symptoms. If there is a bone cyst, imaging will suggest that the corresponding bone can be seen flaky low density foci. 2. Bone inflammation: Bone pain will occur under the effect of inflammatory reaction, especially when the pain will be more obvious during the activity. It is also manifested as flaky low density foci on imaging. 3. Osteonecrosis: Bone necrosis caused by ischemia for various reasons, generally speaking, it is difficult to be detected by X-ray at the early stage of examination, and it needs to be examined by CT or MRI. When abnormal image changes are found in the bone by imaging examination, it is necessary for the doctor to combine the symptoms and signs for identification, and listen to the doctor for further examination to determine the nature of the disease or the specific disease, in order to carry out the treatment as early as possible.