ICD-10 Code C04.9 – Malignant neoplasm of floor of mouth, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C04.9 – Malignant neoplasm of floor of mouth, unspecified
What it is
This code identifies a malignant tumor in the floor of the mouth when the exact subsite is not documented. Use it for primary cancer of that oral cavity region when records do not specify a more precise location.
Clinical signs
Clinical features vary; refer to documentation. Commonly noted findings may include an oral mass, ulceration, pain, bleeding, or difficulty with speech or swallowing, but you should code only what is documented.
When to use this code
Use C04.9 when the provider documents cancer of the floor of the mouth but does not identify the anterior, lateral, or other exact site. It also fits pathology, imaging, or operative reports that confirm malignancy without further localization. If later notes specify a more exact subsite, code the documented detail instead.
Do not use for
Do not use this code for benign oral lesions, dysplasia, or cancers clearly assigned to another oral cavity site. If the record names a different primary site or metastatic disease only, check documentation.
Coding tip
Look for the most specific anatomic wording in the chart before defaulting to unspecified.