Osteitis deformans in neoplastic diseases, unsp forearm

This code signifies Paget's disease of bone (osteitis deformans) occurring in a patient with a neoplastic disease, specifically affecting an unspecified forearm. It indicates a bone remodeling disorder characterized by excessive and disorganized bone formation, which is secondary to or associated with a co-existing cancer.

Use this code when documentation clearly states a diagnosis of Paget's disease of the bone in the forearm, and there is an explicit link or co-occurrence with a neoplastic process. Supporting documentation would include physician notes detailing both conditions and specifying the forearm as the affected site for the osteitis deformans.

• Always code the underlying neoplastic disease first, followed by this code to indicate the manifestation.
• Ensure the documentation specifies "unspecified forearm" if a more precise location (e.g., right or left) is not provided.
• Do not use this code for Paget's disease unrelated to a neoplastic process; use codes from M88.- for those cases.