A 45 yrs male presented with an expansile lesion in the centre of femoral metaphysis. The lesion shows endosteal scalloping & punctuate calcifications. Most likely diagnosis is –
**Core Concept**
The question tests the student's knowledge of bone tumors and their radiological features, specifically the characteristics of a lesion in the metaphyseal region of the femur.
**Why the Correct Answer is Right**
The expansile lesion with endosteal scalloping and punctate calcifications is suggestive of a benign bone tumor, most likely a Chondroblastoma. Chondroblastomas typically occur in the epiphyseal or metaphyseal regions of long bones, with a predilection for the proximal femur. The endosteal scalloping is due to the expansion of the lesion, which erodes the cortical bone. The punctate calcifications are calcified cartilage matrix within the tumor.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is likely to be a malignant bone tumor such as Osteosarcoma, which typically presents with a moth-eaten appearance and cortical destruction, not endosteal scalloping.
* **Option B:** This option could be a Giant Cell Tumor, which usually occurs in the epiphyseal region and is characterized by a "soap bubble" appearance on radiographs, not punctate calcifications.
* **Option C:** This option might be a Fibrous Cortical Defect, which typically presents as a well-defined lytic lesion with a sclerotic border, not endosteal scalloping.
**Clinical Pearl / High-Yield Fact**
Chondroblastomas are typically seen in young adults and are often associated with joint pain and stiffness, making them a diagnostic challenge in the differential diagnosis of bone lesions.
**Correct Answer:** D.