ICD-10 Code C00.5 – Malignant neoplasm of lip, unspecified, inner aspect (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C00.5 – Malignant neoplasm of lip, unspecified, inner aspect
What it is
C00.5 identifies a malignant tumor of the lip located on the inner aspect, when the documentation does not specify a more precise site. Use it for primary lip cancer recorded in this location.
Clinical signs
Clinical features may include a persistent lip lesion, ulceration, induration, bleeding, or pain. Diagnosis is typically confirmed by pathology; clinical features vary, so refer to documentation.
When to use this code
Use this code when the provider documents a malignant neoplasm of the lip on the inner aspect and does not name a more specific subsite. It also fits when the chart states “unspecified” inner lip malignancy. If the record identifies another lip site or a metastatic lesion, choose the documented diagnosis instead.
Do not use for
Do not use C00.5 for benign lip lesions, dysplasia, or nonmalignant ulcers. Also avoid it when the cancer site is documented elsewhere on the lip or when documentation is unclear; check documentation.
Coding tip
Code the exact lip subsite only when the provider documents it; otherwise, keep the unspecified inner-aspect code and query if the location is ambiguous.