Aneurysmal bone cyst, right lower leg

This code represents an aneurysmal bone cyst (ABC), a benign, expansile, osteolytic bone lesion, specifically located in the right lower leg. It is characterized by blood-filled spaces separated by fibrous septa containing osteoclast-like giant cells and reactive woven bone.

Use this code when documentation confirms a diagnosis of an aneurysmal bone cyst affecting the right tibia or fibula. This diagnosis is typically supported by imaging studies (X-ray, MRI) showing characteristic features and often confirmed by biopsy.

• Ensure laterality (right) and specific anatomical site (lower leg) are clearly documented.
• Distinguish from other benign bone tumors or tumor-like conditions, such as fibrous dysplasia or unicameral bone cysts.
• Do not use for pathological fractures unless the fracture is explicitly stated as secondary to the aneurysmal bone cyst.