Mucosal cyst of postmastoidectomy cavity, unspecified ear

This code describes a benign, fluid-filled sac that forms within the lining of the mastoid cavity following a mastoidectomy procedure. This cyst is located in an unspecified ear and is typically a late complication of the surgery, often resulting from entrapped mucosa.

Use this code when documentation explicitly states the presence of a mucosal cyst within a post-mastoidectomy cavity, and the laterality of the ear is not specified. This diagnosis is typically made via imaging (CT or MRI) or direct visualization during otoscopic examination or surgical exploration.

• Ensure documentation clearly specifies "mucosal cyst" and its location within a "postmastoidectomy cavity."
• Avoid using this code if the cyst is not explicitly stated as mucosal or if it's located elsewhere in the ear.
• If the laterality (right or left ear) is documented, use the more specific codes H95.131 (right ear) or H95.132 (left ear).