ICD-10 Code D00.0 – Carcinoma in situ of lip, oral cavity and pharynx (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D00.0 – Carcinoma in situ of lip, oral cavity and pharynx
What it is
D00.0 identifies carcinoma in situ involving the lip, oral cavity, or pharynx. This means abnormal epithelial cells are present but have not invaded deeper tissue.
Clinical signs
Findings may include a persistent mucosal lesion, leukoplakia, erythroplakia, or a suspicious plaque on the lip or in the mouth. Clinical features vary; refer to documentation.
When to use this code
Use this code when the provider documents carcinoma in situ at one of these sites and confirms the lesion is noninvasive. It is appropriate for pathology-supported diagnoses involving the lip, oral cavity, or pharynx. If the record only says dysplasia or a suspicious lesion, check documentation before coding.
Do not use for
Do not use D00.0 for invasive malignancy or for benign oral lesions. If the site is documented elsewhere or the diagnosis is uncertain, check documentation.
Coding tip
Confirm the exact anatomic site and that the pathology or provider states “in situ” before assigning D00.0.