Fibrous dysplasia (monostotic), other site

This code signifies a benign, non-hereditary bone disorder where normal bone is replaced by fibrous tissue and immature woven bone in a single bone (monostotic). This leads to weakened bone structure, potential deformities, and increased fracture risk in an unspecified location other than the skull, facial bones, ribs, or long bones.

Apply this code for documented cases of monostotic fibrous dysplasia affecting an anatomical site not specifically classified elsewhere (e.g., a carpal bone, tarsal bone, or vertebra). Documentation should clearly state "fibrous dysplasia, monostotic" and specify the affected bone if it falls into the "other site" category.

• Ensure documentation specifies "monostotic" to differentiate from polyostotic forms.
• Verify the affected bone is not covered by more specific fibrous dysplasia codes (e.g., M85.01-M85.07).
• Code any associated pathological fractures separately using an appropriate fracture code, with this code as a secondary diagnosis.