Aneurysmal bone cyst, unspecified site

This code signifies a benign, expansile, osteolytic lesion of bone characterized by blood-filled cystic spaces separated by fibrous septa. It represents an aneurysmal bone cyst (ABC) where the specific anatomical location of the cyst is not documented.

This code is appropriate for cases of aneurysmal bone cyst when the medical record does not specify the affected bone or anatomical region. It is used when imaging reports or pathology confirm an ABC but lack site specificity.

• Avoid using this code if a more specific anatomical site (e.g., M85.51- for long bones) is documented.
• Query the provider for clarification on the specific site if possible to allow for more precise coding.
• Consider sequencing with codes for pathological fractures if the ABC has led to a fracture.