**Question:** Radiological finding of Ewings sarcoma is: September 2005

**Core Concept:** Ewings Sarcoma is a malignant bone tumor that primarily affects children and young adults. The tumor arises from primitive neural crest cells and is characterized by the presence of a specific chromosomal translocation. The radiological findings are crucial in diagnosing this disease.

**Why the Correct Answer is Right:** Ewings sarcoma typically presents with characteristic radiological findings. The most common radiological findings include:

1. **Option A (Single or Multiple Osteolytic Lesions**: Ewings Sarcoma is known to cause multiple, well-defined, and lobulated lytic lesions involving the long bones, typically the pelvis, femur, tibia, and humerus. These lesions are characterized by destruction of bone cortex and medulla, with a sclerotic rim that gives it a "punched-out" appearance.

2. **Option C (Enlarged Soft Tissue Masses):**: Ewings Sarcoma may also present with soft tissue masses. These masses are typically tender, circumscribed, and well-defined. They may also be associated with pathologic fractures.

3. **Option D (Signal Intensity on MRI):**: Ewings Sarcoma is typically hyperintense on T2-weighted MRI sequences due to the presence of increased cellularity and increased water content within the tumor cells.

4. **Option B (Enlarged Soft Tissue Masses):**: Although not specific to Ewings Sarcoma, enlarged soft tissue masses are common findings in multiple bone and soft tissue malignancies, making it less specific compared to the other options.

**Why Each Wrong Option is Incorrect:**

1. **Option A (Enlarged Soft Tissue Masses):**: While enlarged soft tissue masses are seen in some cases of Ewings Sarcoma, they are not specific to this disease. Other bone tumors and soft tissue malignancies can also present with soft tissue masses.

2. **Option B (Signal Intensity on MRI):**: Although the MRI finding of hyperintensity on T2-weighted sequences is a common feature in Ewings Sarcoma, it is not specific to this disease. Other bone and soft tissue malignancies may also exhibit similar MRI findings due to increased cellularity and water content within the tumor cells.

3. **Option D (Enlarged Soft Tissue Masses):**: While the presence of soft tissue masses is seen in some cases of Ewings Sarcoma, it is not specific to this disease. Other bone and soft tissue malignancies can also present with soft tissue masses.

**Core Concept:**
Ewings Sarcoma is a high-grade malignant bone tumor that arises from primitive neuroectodermal cells. It is characterized by a specific chromosomal translocation t(11;22)(q24;q12) that leads to the fusion of the EWS and FLI1 genes.

**Why Each Wrong Option is Incorrect:**

1. **Option A (Enlarged Soft Tissue Masses):**: While these masses are seen in some cases of Ewings Sarcoma, they are