A 10 year old boy was found to have a symmetric radiolytic lesion on the X-ray at the upper end of the right humerus after being admitted for fracture of humerus. Such a lesion is present on the left humerus as well. What is the likely pathology?

**Core Concept**
The underlying principle being tested involves the identification of a specific bone pathology characterized by symmetric radiolytic lesions. This condition is related to **bone metabolism disorders** or **genetic conditions** affecting bone health.

**Why the Correct Answer is Right**
Given the symmetric nature and location of the radiolytic lesions at the upper end of both humeri, the likely diagnosis is related to a condition that affects bone density and structure uniformly. This pattern suggests a systemic or genetic condition rather than a localized process.

**Why Each Wrong Option is Incorrect**
**Option A:** This choice might be incorrect because it doesn't typically present with symmetric radiolytic lesions.
**Option B:** Similarly, this option is unlikely due to the lack of characteristic findings that match the described symmetric lesions.
**Option C:** This choice is also incorrect as it does not align with the clinical presentation of symmetric radiolytic lesions in the humeri.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that symmetric bone lesions, especially in a pediatric patient, should prompt consideration of **genetic disorders** or **systemic conditions** like osteogenesis imperfecta or fibrous dysplasia.

**Correct Answer:** D. Osteogenesis Imperfecta.

✓ Correct Answer: A. Unicameral bone cyst