Mucosal cyst of postmastoidectomy cavity, right ear

This code describes the presence of a fluid-filled sac lined with mucous membrane within the surgical space remaining after a mastoidectomy procedure, specifically located in the right ear. This cyst is a complication arising from the prior surgical intervention on the mastoid bone.

Use this code when documentation clearly indicates a mucosal cyst has developed within the post-surgical cavity of the right mastoid. This typically occurs following a mastoidectomy performed for conditions such as chronic otitis media or cholesteatoma. The diagnosis should be confirmed by imaging or direct visualization.

• Ensure documentation specifies "mucosal cyst" and not another type of cyst or granuloma within the cavity.
• Verify the laterality is explicitly stated as "right ear" to avoid incorrect coding.
• Consider sequencing this code after any underlying condition that necessitated the original mastoidectomy, if still active and relevant.