ICD-10 Code C00.6 – Malignant neoplasm of commissure of lip, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C00.6 – Malignant neoplasm of commissure of lip, unspecified
What it is
This code identifies a malignant tumor of the lip commissure, the corner where the upper and lower lips meet. Use it when the record says the cancer is in that location and no further detail is given.
Clinical signs
Clinical features vary; refer to documentation. Commonly, a lip cancer may present as a persistent nonhealing lesion, ulcer, thickened area, or bleeding at the lip corner.
When to use this code
Use C00.6 when the provider documents a primary malignant neoplasm at the commissure of the lip and does not specify a more detailed site. It also fits pathology, oncology, or surgical notes that clearly localize the tumor to the lip corner. Check documentation if laterality or another lip subsite is stated.
Do not use for
Do not use this code for benign lip lesions, premalignant changes, or cancers of other oral sites. If the lesion is documented elsewhere on the lip, code the stated site instead.
Coding tip
Code the exact anatomic wording in the note; if “commissure” is not documented, verify the site before assigning C00.6.