What imaging finding is characteristic of Paget's disease of bone?

Paget's disease of bone is characterized by abnormal and excessive bone remodeling, which leads to distinctive changes in bone structure. The correct imaging finding is the presence of dense, expanded bone that exhibits a chaotic mosaic appearance. This is due to the disorganized trabecular pattern and increased osteoblastic and osteoclastic activity associated with the condition. On X-ray, this appearance results from the abnormal architecture of the bone, where normal lamellar bone is replaced by disorganized woven bone, leading to enlarged and weakened bones.

The other options do not accurately represent the characteristic imaging findings associated with Paget's disease. Thinning cortex is typically observed in other conditions, such as osteoporosis. Pathological fractures can occur in patients with Paget's disease due to the structural changes and weakened bones, but they are not an imaging finding specific to the disease. Increased bone density without pain is a feature that could be seen in various other conditions, not specifically indicative of Paget's disease, which may or may not present with pain depending on the involvement of other surrounding structures or potential complications.