CT T2 T1 post-gad

Diagnosis: Pagets disease

Pagets disease is a fairly common disorder affecting about 3% of people over 40 years of age. The most involved bones include the pelvis, femur, skull, tibia, and spine. The etiology is unknown, but many believe Pagets disease has a viral cause. The histological process underlying Pagets disease is osteoclastic resorption of bony trabeculae. It is characterized initially by an osteolytic phase where the bone becomes demineralized with increased vascularity and connective tissue. This is followed by a mixed phase of lytic and sclerotic bone with a characteristic cotton wool appearance. The end stage of Pagets disease is a sclerotic phase where the fibrous tissue is replaced by thickened, abnormal sclerotic bone. Complications of Pagets disease include deafness from involvement of the temporal bone (Beethoven), basilar invagination, and pathologic fracture. Malignant transformation has been reported in up to 1% of cases of Pagets disease although this is controversial.

On imaging, the bone is typically thickened with a variable amount of lytic and sclerotic change. The T1 signal of the involved marrow is diminished secondary to replacement of marrow fat by fibrous tissue. There may be enhancement due to the increased vascularity of the Pagetic bone.

The etiology for the dural thickening and enhancement here is probably due to inflammation from adjacent Pagetic bone. The changes are most apparent where the frontal bones are most involved. This patient has no other reason for the dural findings. Other entities which may be considered in the differential for Pagets disease include osteopetrosis, fibrous dysplasia, and metastases. Fibrous dysplasia and osteopetrosis present in younger patients. In addition, osteopetrosis produces a more confluent, avascular thickening of bone. A metastatic lesion may mimic a focal area of Paget's disease. Related Cases

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