C31.9Billable

Malignant neoplasm of accessory sinus, unspecified

Chapter
2. Neoplasms
Category
C31
Effective date
October 1, 2026

Related codes in category C31

C31Malignant neoplasm of accessory sinusesC31.0Malignant neoplasm of maxillary sinusYesC31.1Malignant neoplasm of ethmoidal sinusYesC31.2Malignant neoplasm of frontal sinusYesC31.3Malignant neoplasm of sphenoid sinusYesC31.8Malignant neoplasm of overlapping sites of accessory sinusesYes

Frequently asked questions

What is ICD-10 code C31.9?

C31.9 is an ICD-10-CM diagnosis code for Malignant neoplasm of accessory sinus, unspecified.

Is C31.9 a billable code?

Yes. C31.9 is billable and specific enough to be used on a claim.

What ICD-10-CM chapter is C31.9 in?

C31.9 falls under Chapter 2: Neoplasms.

When did C31.9 become effective?

C31.9 has been effective since October 1, 2026, per the CMS/CDC ICD-10-CM annual release.

What other codes are related to C31.9?

C31.9 belongs to category C31, which includes 6 other codes — see the related codes list on this page.

ICD-10-CM data maintained by CDC/CMS (public domain). Always verify codes with authoritative sources before making coding or billing decisions.