C31: Malignant neoplasm of accessory sinuses

Codes under C31 (Malignant neoplasm of accessory sinuses). A ✓ marks a billable (fully specified) code; category codes without a ✓ are not billable on their own.

Code	Description	Billable
C31.0	Malignant neoplasm of maxillary sinus	✓
C31.1	Malignant neoplasm of ethmoidal sinus	✓
C31.2	Malignant neoplasm of frontal sinus	✓
C31.3	Malignant neoplasm of sphenoid sinus	✓
C31.8	Malignant neoplasm of overlapping sites of accessory sinuses	✓
C31.9	Malignant neoplasm of accessory sinus, unspecified	✓

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Informational only, not coding or medical advice. Verify against the official ICD-10-CM (FY2026) and your payer's guidelines.

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