ICD-10 Code D00.00 – Carcinoma in situ of oral cavity, unspecified site (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D00.00 – Carcinoma in situ of oral cavity, unspecified site
What it is
This code identifies a preinvasive malignant lesion in the oral cavity, with the site not further specified. The abnormal cells are confined to the surface layer and have not invaded deeper tissue.
Clinical signs
Findings may include a persistent oral mucosal patch, plaque, or ulcer that does not resolve. Clinical features vary; refer to documentation, biopsy results, and the provider’s site description.
When to use this code
Use D00.00 when the record documents carcinoma in situ involving the oral cavity but does not name a more specific oral site. Apply it after pathology or specialist documentation confirms the diagnosis. If the note identifies a specific oral subsite, code that more precise option instead.
Do not use for
Do not use this code for invasive oral cancer, dysplasia without carcinoma in situ, or lesions outside the oral cavity. Check documentation if the site is unclear or if the pathology wording is ambiguous.
Coding tip
Code the most specific oral site documented; use D00.00 only when the provider does not specify the exact location.