ICD-10 Code C01 – Malignant neoplasm of base of tongue (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C01 – Malignant neoplasm of base of tongue
What it is
C01 identifies a malignant tumor arising in the base of the tongue, the posterior third of the tongue near the oropharynx. Use it when documentation specifies cancer at this exact site.
Clinical signs
Clinical features vary; refer to documentation. Commonly recorded findings include a visible or palpable tongue-base mass, sore throat, dysphagia, odynophagia, referred ear pain, or neck lymphadenopathy.
When to use this code
Use C01 when the provider documents primary cancer of the base of tongue, including biopsy-confirmed malignant neoplasm at that location. It also fits encounters for evaluation, staging, or follow-up of a documented tongue-base malignancy. Check documentation if the site is described only as oral cavity, tongue, or oropharynx.
Do not use for
Do not use C01 for benign tongue lesions, dysplasia, or cancers of other oral sites. If the record does not clearly identify the base of tongue as the primary site, check documentation.
Coding tip
Verify the exact anatomic site in pathology, operative, or oncology notes before assigning C01.