Osteitis deformans in neoplastic diseases, right upper arm

This code describes Paget's disease of bone (osteitis deformans) occurring as a secondary manifestation in a patient with a neoplastic disease, specifically affecting the right upper arm. It indicates a localized bone remodeling disorder characterized by excessive bone resorption and disorganized new bone formation, linked to an underlying malignancy.

Apply this code when documentation clearly states a diagnosis of osteitis deformans in the right upper arm, and explicitly links it to an existing neoplastic disease. This typically occurs when the malignancy or its treatment contributes to the development or exacerbation of Paget's disease. Supporting documentation would include pathology reports, imaging studies, and physician notes detailing both conditions and their relationship.

• Always code the underlying neoplastic disease first, as this code represents a manifestation of that disease.
• Ensure documentation specifies "right upper arm" to justify the laterality and anatomical site.
• Differentiate from primary Paget's disease of bone (M88.-) which is not associated with a neoplastic process.