ICD-10 Code C04.0 – Malignant neoplasm of anterior floor of mouth (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C04.0 – Malignant neoplasm of anterior floor of mouth
What it is
C04.0 identifies a malignant tumor located in the front portion of the floor of the mouth. Use it when documentation specifically states the anterior floor of mouth as the primary site.
Clinical signs
Common findings include a persistent oral lesion, ulcer, mass, pain, bleeding, or difficulty with chewing and speaking. Clinical features vary; refer to documentation.
When to use this code
Use C04.0 when the provider documents primary cancer of the anterior floor of mouth, including pathology or operative notes that confirm this exact site. You should code it when the tumor origin is clearly in the front floor of the mouth and not described more generally.
Do not use for
Do not use this code for cancers of other oral cavity sites, such as the tongue, gum, palate, or posterior floor of mouth. Check documentation if the primary site is unclear or overlapping.
Coding tip
Always verify the exact anatomic site in the pathology, imaging, or provider note before assigning C04.0.