Malignant neoplasm of lip, unspecified, inner aspect

This code signifies a cancerous tumor originating from the inner surface of the lip, where the specific subsite (e.g., upper or lower lip) is not documented. It represents a primary malignancy of the labial mucosa, excluding the vermilion border or outer skin.

Apply this code when medical record documentation confirms a malignant neoplasm of the lip, and the physician explicitly states "inner aspect" without further specifying upper or lower. This code is appropriate when pathology confirms malignancy and the tumor's exact location within the inner lip is not precisely identified.

• Do not use this code if the documentation specifies "upper inner lip" or "lower inner lip"; use more specific codes (C00.3 or C00.4) instead.
• Ensure the pathology report confirms malignancy; otherwise, consider codes for benign neoplasms or uncertain behavior.
• Sequence this code as the primary diagnosis when it is the reason for the encounter or treatment.