Malignant neoplasm of other sites of floor of mouth

This code signifies the presence of a cancerous tumor originating in various less common areas of the floor of the mouth, excluding the anterior two-thirds and specific sublingual gland sites. These malignancies typically arise from the mucosal lining or underlying glandular tissue in these regions.

Apply this code when documentation specifies a primary malignant neoplasm located in an unspecified or "other" site within the floor of the mouth. This includes areas not covered by more specific anatomical codes for the floor of mouth. Supporting documentation should clearly indicate the malignant nature and the precise, albeit less common, location within the floor of the mouth.

• Ensure the documentation explicitly states "malignant" and specifies a site within the floor of the mouth that isn't more precisely defined elsewhere (e.g., anterior two-thirds).
• Differentiate from benign neoplasms of the floor of mouth or malignant neoplasms of adjacent structures like the tongue or sublingual gland, which have distinct codes.
• Always sequence this code as the primary diagnosis when it represents the reason for the encounter or treatment.