Osteitis deformans in neoplastic diseases, left forearm

This code signifies Paget's disease of bone, specifically affecting the left forearm, when it occurs secondary to a neoplastic process. It describes a localized bone remodeling disorder characterized by excessive bone resorption and disorganized bone formation, directly attributable to the presence of a tumor.

Use this code when documentation clearly states a diagnosis of osteitis deformans (Paget's disease) in the left forearm, and explicitly links its etiology to an underlying neoplastic disease. This code is appropriate for cases where the Paget's disease is a direct consequence or manifestation of cancer, rather than an idiopathic primary condition.

• Always sequence the underlying neoplastic disease code first, as it is the primary etiology.
• Ensure documentation specifies "left forearm" and the causal link to a neoplasm; otherwise, a more general or unspecified Paget's code may be appropriate.
• Distinguish from idiopathic Paget's disease (M88.-) which is not caused by a neoplasm.