Aneurysmal bone cyst, other site

This code signifies the presence of a benign, expansile, blood-filled lesion within bone tissue, specifically located in an anatomical region other than the long bones of the extremities, vertebrae, or pelvis. It represents a non-neoplastic, osteolytic process characterized by cystic spaces separated by fibrous septa containing osteoclast-like giant cells.

Apply this code when documentation confirms an aneurysmal bone cyst (ABC) diagnosed in a site not covered by more specific codes (e.g., skull, facial bones, ribs, sternum, scapula, clavicle, small bones of hands/feet). Supporting documentation should include pathology reports, imaging studies (X-ray, MRI, CT), and physician notes detailing the lesion's location and characteristics consistent with an ABC.

• Ensure the documentation explicitly rules out other bone lesions, such as giant cell tumor or simple bone cyst, which can have similar radiographic appearances.
• Verify the exact anatomical site to avoid miscoding with more specific ABC codes (e.g., M85.50-M85.57).
• Code any associated pathological fracture separately if present, using an appropriate fracture code.