Which disease is characterized by chronic inflammation leading to the thickening and softening of bones?

Paget disease, also known as osteitis deformans, is characterized by abnormal and excessive bone remodeling, leading to chronic inflammation that results in the thickening and softening of bones. This condition often affects the pelvis, skull, spine, and legs, causing affected bones to become enlarged but weak. As the disease progresses, the normal bone architecture is disrupted, which can lead to pain, deformity, and increased risk of fractures.

The hallmark of Paget disease is the imbalance between bone resorption and bone formation. The osteoclasts, which are responsible for bone resorption, become overactive, causing areas of the bone to be broken down at an accelerated rate. In response, osteoblasts work to create new bone, but often this new bone is structurally inferior to normal bone, resulting in the characteristic thickened yet weaker bones. Symptoms can include bone pain, joint pain, and structural deformities, which can significantly impact a person's quality of life.

Understanding Paget disease can also provide insights into the importance of bone health and the implications of chronic inflammatory processes within the body.