2027 ICD-10-CM Diagnosis Code C79.83Secondary malignant neoplasm of oral cavity
ICD-10-CM Codes›C00–D49›C76-C80›C79
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- New 2027 Code
C79.83 is a billable ICD-10-CM diagnosis code for secondary malignant neoplasm of oral cavity. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 826 through 830, 843 through 845. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 19 closely related codes.
Code Identity
Code Classification
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to C79.83: its own notes plus those printed at C79 and Chapter 2. A note printed at a category, block or chapter applies to every code under it.
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
Notes
General instructions on how these codes are used.
- Functional activity
- All neoplasms are classified in this chapter, whether they are functionally active or not. An additional code from Chapter 4 may be used, to identify functional activity associated with any neoplasm.
- Morphology [Histology]
- Chapter 2 classifies neoplasms primarily by site (topography), with broad groupings for behavior, malignant, in situ, benign, etc. The Table of Neoplasms should be used to identify the correct topography code. In a few cases, such as for malignant melanoma and certain neuroendocrine tumors, the morphology (histologic type) is included in the category and codes.
- Primary malignant neoplasms overlapping site boundaries
- A primary malignant neoplasm that overlaps two or more contiguous (next to each other) sites should be classified to the subcategory/code .8 ('overlapping lesion'), unless the combination is specifically indexed elsewhere. For multiple neoplasms of the same site that are not contiguous, such as tumors in different quadrants of the same breast, codes for each site should be assigned.
- Malignant neoplasm of ectopic tissue
- Malignant neoplasms of ectopic tissue are to be coded to the site mentioned, e.g., ectopic pancreatic malignant neoplasms are coded to pancreas, unspecified (C25.9).
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name C79.83, its category, or a range that includes it.
Applicable To 2
These notes mention C79.83.
Table of NeoplasmsClinical
Anatomical sites in the Table of Neoplasms that reference this code family.
Code History & ChangesHistory
New Code C79.83 was added to the ICD-10-CM code set for FY 2027, effective October 1, 2026.
Replacement C79.83 replaces the following previously assigned code(s):
- C79.89 - Secondary malignant neoplasm of other specified sites
Questions About C79.83Overview
What is the ICD-10 code for secondary malignant neoplasm of oral cavity?
The ICD-10-CM code for secondary malignant neoplasm of oral cavity is C79.83 (sometimes written as C7983). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is C79.83 (Secondary malignant neoplasm of other specified sites) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report secondary malignant neoplasm of oral cavity on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does C79.83 group to?
When secondary malignant neoplasm of oral cavity is the principal diagnosis on an inpatient stay, it groups to MS-DRG 844, 827, 829, 843, 828, 826, 830, 845, with relative weights from 0.8443 to 4.7560 depending on complications. Higher weights mean higher Medicare reimbursement.
Is C79.83 a CC or MCC?
CMS lists C79.83 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 19 closely related codes in its exclusion list.
Can C79.83 be reported with a code from C7B?
Not as a rule. The Excludes1 note at C79, which applies to C79.83, lists "secondary carcinoid tumors (C7B.-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
