Carcinoma in situ of tongue

This code signifies the presence of abnormal, non-invasive epithelial cells confined to the mucosal layer of the tongue, indicating an early stage of cancer that has not spread beyond its original site. It represents a pre-invasive malignant condition where the tumor cells have not penetrated the basement membrane.

Use this code when diagnostic biopsy or surgical pathology reports confirm carcinoma in situ of any part of the tongue. Documentation should clearly state "carcinoma in situ," "intraepithelial neoplasia grade III," or "severe dysplasia" of the tongue, indicating the highest grade of pre-invasive malignancy.

• Ensure the pathology report explicitly states "in situ" or an equivalent high-grade pre-invasive term for the tongue.
• Do not use this code for invasive squamous cell carcinoma of the tongue; refer to the C01-C02 series for those cases.
• Sequence this code as the primary diagnosis when it is the reason for the encounter, such as for excision or further diagnostic workup.