Is ICD-10-CM code C31 billable?

No, C31 (Malignant neoplasm of accessory sinuses) is a non-billable ICD-10-CM code. It must be coded to a more specific subcategory before it can be used for reimbursement.

What chapter does ICD-10-CM code C31 belong to?

C31 belongs to Chapter 2 of the ICD-10-CM tabular list: C00–D49 (Neoplasms).

C31Non-billable

Malignant neoplasm of accessory sinuses

Neoplasms·Malignant neoplasms of respiratory and intrathoracic organs (C30-C39)·category·FY 2026

Use a more specific code (6 billable)

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

C30-C39 Parent Instructions

Includes

malignant neoplasm of middle ear

Excludes1(Not coded here. Use a different code.)

mesothelioma (C45.-)

Clinical Hierarchy

BillableHas subcodes

CH2Neoplasms (C00-D49)

C30-C39Malignant neoplasms of respiratory and intrathoracic organs (C30-C39)

C31Malignant neoplasm of accessory sinusesNot billable

C31.0Malignant neoplasm of maxillary sinusBillable

C31.1Malignant neoplasm of ethmoidal sinusBillable

C31.2Malignant neoplasm of frontal sinusBillable

C31.3Malignant neoplasm of sphenoid sinusBillable

C31.8Malignant neoplasm of overlapping sites of accessory sinusesBillable

C31.9Malignant neoplasm of accessory sinus, unspecifiedBillable

MS-DRG Classification

2026

No direct MS-DRG triggers identified.