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ICD-10-CM 2027 diagnosis code

C79.83Secondary malignant neoplasm of oral cavity

✓ Billable / specificNew for 2027CC — complication/comorbidity

C79.83 is a valid, billable ICD-10-CM code for secondary malignant neoplasm of oral cavity. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS, effective October 1, 2026. Updated September 29, 2026. About our data

About C79.83

C79.83 is the ICD-10-CM diagnosis code for secondary malignant neoplasm of oral cavity. It belongs to category C79 (secondary malignant neoplasm of other and unspecified sites), block C76-C80 (malignant neoplasms of ill-defined, other secondary and unspecified sites) 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 C79.8 (secondary malignant neoplasm of other specified sites), C79.83 is specifically for secondary malignant neoplasm of oral cavity. Related codes cover breast (C79.81), genital organs (C79.82) and other specified sites (C79.89).

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 826 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Major O.R. Procedures with MCC, relative weight 4.7581), DRG 827 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Major O.R. Procedures with CC, relative weight 2.3896), DRG 828 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Major O.R. Procedures without CC/MCC, relative weight 1.6955), DRG 829 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Other Procedures with CC/MCC, relative weight 3.1281), DRG 830 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Other Procedures without CC/MCC, relative weight 1.4859), DRG 843 (Other Myeloproliferative Disorders or Poorly Differentiated Neoplastic Diagnoses with MCC, relative weight 1.9453) and 2 more, in MDC 17 (Myeloproliferative Diseases and Disorders, Poorly Differentiated Neoplasms), 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 was added in FY2027, effective October 1, 2026.

Notes that apply from higher levels

Instructions written at a parent level also apply to C79.83.

› From C79 Secondary malignant neoplasm of other and unspecified sites
Excludes1
  • secondary carcinoid tumors (C7B.-)
  • secondary neuroendocrine tumors (C7B.-)

Broader instructions also apply from Chapter 2: Neoplasms.

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.

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
  • FY2027 (effective 10/1/2026): Added

Common questions about C79.83

Is C79.83 billable?

Yes. C79.83 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can C79.83 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict C79.83 as a principal diagnosis.

Is C79.83 a CC or MCC?

C79.83 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does C79.83 group to?

C79.83 is used in the MS-DRG v44.0 logic for MS-DRG 826 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Major O.R. Procedures with MCC), MS-DRG 827 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Major O.R. Procedures with CC), MS-DRG 828 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Major O.R. Procedures without CC/MCC), MS-DRG 829 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Other Procedures with CC/MCC), MS-DRG 830 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Other Procedures without CC/MCC), MS-DRG 843 (Other Myeloproliferative Disorders or Poorly Differentiated Neoplastic Diagnoses with MCC) and 2 more. Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

Did C79.83 change for 2027?

Yes. For FY2027 (effective October 1, 2026) it was added to the code set.