Abnormal resorption followed by apposition of bone leaving deeply stained lines, which occurs in Paget’s disease. These lines are known as:
**Core Concept**
Paget's disease is a chronic bone disorder characterized by abnormal bone resorption followed by abnormal bone apposition, leading to deformities and an increased risk of fractures. This process results in the formation of characteristic bone lesions.
**Why the Correct Answer is Right**
The abnormal bone resorption in Paget's disease is mediated by osteoclasts, which break down the bone matrix. This is followed by the apposition of new bone tissue by osteoblasts. The resorption process leaves behind deeply stained lines, which are a hallmark of the disease. These lines are a result of the uneven resorption and apposition of bone, leading to the characteristic mosaic pattern seen in Paget's disease.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not describe the characteristic bone lesions seen in Paget's disease.
**Option B:** This option is incorrect because it is a term more commonly associated with osteoporosis, which is a different bone disorder.
**Option C:** This option is incorrect because it is a term more commonly associated with bone tumors, which are a different type of bone lesion.
**Clinical Pearl / High-Yield Fact**
The characteristic bone lesions seen in Paget's disease can be remembered using the mnemonic "COTTAGE", which stands for: Cortical resorption, Osteoblastic activity, Trabecular thickening, Trabecular thinning, Giant osteoclasts, and Endosteal new bone formation.
**Correct Answer:** C. Cotton wool appearance