ICD-10 Code H95.139 – Mucosal cyst of postmastoidectomy cavity, unspecified ear (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code H95.139 – Mucosal cyst of postmastoidectomy cavity, unspecified ear
What it is
This code identifies a mucosal cyst developing in a postmastoidectomy cavity, when the affected ear is not specified. It documents a localized cystic lesion in the surgical mastoid cavity rather than a new infection or generalized ear disorder.
Clinical signs
Clinical features vary; refer to documentation. Notes may describe a cystic mass, cavity fullness, drainage, or persistent postoperative ear symptoms seen on otologic exam or imaging.
When to use this code
Use H95.139 when the provider documents a mucosal cyst in a postmastoidectomy cavity and does not specify right or left ear. It is appropriate for postoperative follow-up, ENT evaluation, or imaging findings that identify this lesion. If the record names a specific ear, code that laterality instead.
Do not use for
Do not use this code for general mastoiditis, uncomplicated postoperative pain, or an unspecified ear disorder without a documented mucosal cyst. Check documentation if the note only mentions a mastoid cavity abnormality.
Coding tip
Verify both the postoperative cavity finding and laterality before assigning H95.139.