Mucosal cyst of postmastoidectomy cavity, bilateral ears

This code describes the presence of a mucosal cyst within the postmastoidectomy cavity affecting both ears. This cyst is a benign, fluid-filled sac that can develop as a complication following a mastoidectomy procedure. It typically arises from entrapped mucosal lining within the surgical cavity.

Use this code when documentation explicitly states a mucosal cyst is present in the mastoidectomy cavity of both the left and right ears. This diagnosis is typically made via imaging studies (e.g., CT scan) or direct visualization during otoscopic examination or surgical exploration.

• Ensure documentation specifies "bilateral ears" for accurate code assignment.
• Do not confuse with cholesteatoma (H71.-), which is a different type of growth within the mastoid.
• Code also any associated symptoms or complications, such as otorrhea or hearing loss, if documented.