Geographic lytic lesions in vault of skull with bevelled edges are seen with
**Core Concept**
Geographic lytic lesions with bevelled edges in the vault of the skull are characteristic of a specific type of bone pathology. These lesions result from the destructive process of bone resorption, which is often associated with certain types of neoplasms or metabolic disorders. The bevelled edges of these lesions are a distinctive feature, indicating a specific pattern of bone destruction.
**Why the Correct Answer is Right**
The correct answer is associated with **Multiple Myeloma**. Multiple myeloma is a malignant neoplasm of plasma cells that can cause bone destruction through the production of osteoclast-activating factors and the direct invasion of bone marrow by malignant cells. The geographic lytic lesions seen in multiple myeloma often have bevelled edges due to the initial lytic destruction of bone followed by a sclerotic border as the body attempts to repair the damage. The vault of the skull is a common site for these lesions, particularly in the context of multiple myeloma.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because while **Metastatic Carcinoma** can cause lytic bone lesions, the characteristic bevelled edges are more typical of multiple myeloma.
* **Option B:** This option is incorrect because **Fibrous Dysplasia** typically presents with ground-glass appearance of bone and does not usually have bevelled edges.
* **Option C:** This option is incorrect because **Paget's Disease** typically presents with mixed lytic and sclerotic lesions and does not usually have bevelled edges.
**Clinical Pearl / High-Yield Fact**
The "punched-out" appearance of lytic lesions in the skull is a classic radiographic feature of multiple myeloma. This appearance is due to the destructive process of bone resorption, which can be so extensive that it creates a clear-cut defect in the bone.
**Correct Answer:** D.