Path fx in oth disease, unsp humerus, subs for fx w malunion

This code signifies a pathological fracture of an unspecified humerus that occurred due to an underlying disease process, not trauma. It specifically indicates that the patient is in a subsequent phase of care for this fracture, and the bone has healed in an anatomically incorrect or misaligned position (malunion).

Apply this code when documentation clearly states a pathological fracture of the humerus, without specifying left or right, and the patient is being treated for a malunion during a follow-up encounter. The underlying disease causing the pathological fracture should also be documented and coded.

• Always sequence the underlying disease responsible for the pathological fracture first, followed by this code.
• Distinguish carefully between malunion (M84.6-) and nonunion (M84.4-); this code is specific to malunion.
• Ensure the documentation specifies "unspecified humerus" if laterality is not provided; otherwise, use a more specific laterality code.