Solitary bone cyst, unspecified humerus

This code signifies the presence of a single, fluid-filled lesion within the bone of an unspecified humerus. These benign cysts, also known as unicameral bone cysts, are typically asymptomatic but can weaken the bone, leading to pathological fractures.

Use this code when documentation confirms a solitary bone cyst located in the humerus, and the specific side (left or right) is not documented or is unknown. This code is appropriate for initial diagnosis, follow-up, or when a pathological fracture is attributed to such a cyst in an unspecified humerus.

• Ensure the documentation clearly states "solitary" or "unicameral" and specifies the humerus as the affected bone.
• If the laterality (left or right humerus) is specified, use the more specific codes M85.421 (right) or M85.422 (left).
• Do not use this code for aneurysmal bone cysts or other types of bone tumors; refer to the appropriate codes for those conditions.