Aneurysmal bone cyst, left lower leg

This code identifies a benign, lytic bone lesion characterized by blood-filled spaces separated by fibrous septa, specifically located in the left lower leg. It represents a non-neoplastic, expansile lesion that can cause pain, swelling, and pathological fractures.

Use this code when documentation confirms the diagnosis of an aneurysmal bone cyst affecting the tibia or fibula of the left leg. This diagnosis is typically established through imaging studies (X-ray, MRI) and often confirmed by biopsy.

• Ensure laterality is clearly documented as "left lower leg" to support this specific code.
• Distinguish from other benign bone tumors or cysts, such as unicameral bone cysts or fibrous dysplasia.
• If a pathological fracture is also present due to the cyst, code the fracture first, followed by this code as a secondary diagnosis.