Osteitis deformans in neoplastic diseases, other site

This code describes Paget's disease of bone (osteitis deformans) that occurs as a secondary manifestation or complication of a neoplastic disease, affecting an "other" site not specified elsewhere. It indicates bone remodeling abnormalities and increased bone turnover directly attributable to the presence of cancer.

Use this code when documentation clearly links a patient's osteitis deformans to an underlying malignancy, and the affected bone site is not specifically categorized by other M90.6 subcategories (e.g., skull, vertebrae, pelvis, limb). Supporting documentation would include physician notes detailing the diagnosis of Paget's disease, the co-occurring neoplastic condition, and the causal relationship between the two.

• Always sequence the underlying neoplastic disease code first, as it is the etiology of the osteitis deformans.
• Ensure the documentation specifies an "other" site for the osteitis deformans; if a specific site (e.g., skull, vertebra) is mentioned, a more precise M90.6 subcategory should be used.
• Distinguish from primary Paget's disease (M88.-) which is not linked to a neoplastic process.