ICD-10 Code C09 – Malignant neoplasm of tonsil (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C09 – Malignant neoplasm of tonsil
What it is
C09 identifies a malignant tumor arising in the tonsil. Use it when the record documents cancer of the tonsil, including unspecified tonsillar malignancy.
Clinical signs
Clinical features vary; refer to documentation. Commonly noted findings may include a tonsillar mass, sore throat, dysphagia, or a neck mass, but you should code only what is documented.
When to use this code
Use C09 when the provider diagnoses primary malignant neoplasm of the tonsil and does not specify a more exact subsite. It also fits initial or ongoing encounters for documented tonsillar cancer. If laterality or a more specific site is stated, code that level instead.
Do not use for
Do not use C09 for benign tonsillar disease, inflammation, or metastatic cancer to the tonsil. Check documentation if the tumor site is another oropharyngeal structure.
Coding tip
Verify the exact anatomic site in the note, because oropharyngeal cancers may be coded to a more specific subcategory when documented.