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ICD-10-CM 2027 diagnosis code

C31.2Malignant neoplasm of frontal sinus

✓ Billable / specific

C31.2 is a valid, billable ICD-10-CM code for malignant neoplasm of frontal sinus. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About C31.2

C31.2 is the ICD-10-CM diagnosis code for malignant neoplasm of frontal sinus. It belongs to category C31 (malignant neoplasm of accessory sinuses), block C30-C39 (malignant neoplasms of respiratory and intrathoracic organs) and chapter 2 (neoplasms). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within C31 (malignant neoplasm of accessory sinuses), C31.2 is specifically for malignant neoplasm of frontal sinus. Related codes cover maxillary sinus (C31.0), ethmoidal sinus (C31.1), sphenoid sinus (C31.3), overlapping sites of accessory sinuses (C31.8) and accessory sinus, unspecified (C31.9).

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 011 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy with MCC, relative weight 5.6154), DRG 012 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy with CC, relative weight 4.381), DRG 013 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy without CC/MCC, relative weight 2.7307), DRG 146 (Ear, Nose, Mouth and Throat Malignancy with MCC, relative weight 2.1329), DRG 147 (Ear, Nose, Mouth and Throat Malignancy with CC, relative weight 1.3055) and DRG 148 (Ear, Nose, Mouth and Throat Malignancy without CC/MCC, relative weight 0.8008), in Pre-MDC and MDC 03 (Diseases and Disorders of the Ear, Nose, Mouth and Throat), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 160.4 (malignant neoplasm of frontal sinus).

Notes that apply from higher levels

Instructions written at a parent level also apply to C31.2.

Table of Drugs & Neoplasms entries

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

ICD-9-CM equivalent

Converter →
  • 160.4Malignant neoplasm of frontal sinusexact

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about C31.2

Is C31.2 billable?

Yes. C31.2 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can C31.2 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict C31.2 as a principal diagnosis.

Is C31.2 a CC or MCC?

No. C31.2 is neither a CC nor an MCC under MS-DRG v44.0.

What DRG does C31.2 group to?

C31.2 is used in the MS-DRG v44.0 logic for MS-DRG 011 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy with MCC), MS-DRG 012 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy with CC), MS-DRG 013 (Tracheostomy for Face, Mouth and Neck Diagnoses or Laryngectomy without CC/MCC), MS-DRG 146 (Ear, Nose, Mouth and Throat Malignancy with MCC), MS-DRG 147 (Ear, Nose, Mouth and Throat Malignancy with CC) and MS-DRG 148 (Ear, Nose, Mouth and Throat Malignancy without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for C31.2?

The CMS General Equivalence Mappings map C31.2 to ICD-9-CM 160.4.