2027 ICD-10-CM Diagnosis Code C79Secondary malignant neoplasm of other and unspecified sites

ICD-10-CM Codes›C00–D49›C76-C80›C79

ICD-10-CM C79
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

C79 is a non-billable ICD-10-CM category code for secondary malignant neoplasm of other and unspecified sites, so it cannot be submitted on claims. Use a more specific code from this category instead, such as C79.00, C79.01, C79.02, and C79.10.

Code Identity

ICD-10-CM Code
C79
Billable Status
No — Non-Billable Category
Code Describes
Secondary malignant neoplasm of other and unspecified sites
Short Description
Secondary malignant neoplasm of other and unspecified sites
Same as the full description in the CMS dataset.
Chapter
C76-C80
Malignant neoplasms of ill-defined, other secondary and unspecified sites

Code Classification

ChapterC00–D49Neoplasms
SectionC76-C80Malignant neoplasms of ill-defined, other secondary and unspecified sites
CategoryC79Secondary malignant neoplasm of other and unspecified sites
This CodeC79Secondary malignant neoplasm of other and unspecified sites

Specific Coding for Secondary malignant neoplasm of other and unspecified sitesOverview

Non-specific codes like C79 require more characters. Use one of these billable codes instead:

  • C79.0 for Secondary malignant neoplasm of kidney and renal pelvis

  • Use C79.00 for Secondary malignant neoplasm of unspecified kidney and renal pelvis

  • Use C79.01 for Secondary malignant neoplasm of right kidney and renal pelvis

  • Use C79.02 for Secondary malignant neoplasm of left kidney and renal pelvis

  • C79.1 for Secondary malignant neoplasm of bladder and other and unspecified urinary organs

  • Use C79.10 for Secondary malignant neoplasm of unspecified urinary organs

  • Use C79.11 for Secondary malignant neoplasm of bladder

  • Use C79.19 for Secondary malignant neoplasm of other urinary organs

  • Use C79.2 for Secondary malignant neoplasm of skin

  • C79.3 for Secondary malignant neoplasm of brain and cerebral meninges

  • Use C79.31 for Secondary malignant neoplasm of brain

  • Use C79.32 for Secondary malignant neoplasm of cerebral meninges

  • C79.4 for Secondary malignant neoplasm of other and unspecified parts of nervous system

  • Use C79.40 for Secondary malignant neoplasm of unspecified part of nervous system

  • Use C79.49 for Secondary malignant neoplasm of other parts of nervous system

  • C79.5 for Secondary malignant neoplasm of bone and bone marrow

  • Use C79.51 for Secondary malignant neoplasm of bone

  • Use C79.52 for Secondary malignant neoplasm of bone marrow

  • C79.6 for Secondary malignant neoplasm of ovary

  • Use C79.60 for Secondary malignant neoplasm of unspecified ovary

  • Use C79.61 for Secondary malignant neoplasm of right ovary

  • Use C79.62 for Secondary malignant neoplasm of left ovary

  • Use C79.63 for Secondary malignant neoplasm of bilateral ovaries

  • C79.7 for Secondary malignant neoplasm of adrenal gland

  • Use C79.70 for Secondary malignant neoplasm of unspecified adrenal gland

  • Use C79.71 for Secondary malignant neoplasm of right adrenal gland

  • Use C79.72 for Secondary malignant neoplasm of left adrenal gland

  • C79.8 for Secondary malignant neoplasm of other specified sites

  • Use C79.81 for Secondary malignant neoplasm of breast

  • Use C79.82 for Secondary malignant neoplasm of genital organs

  • Use C79.83 for Secondary malignant neoplasm of oral cavity

  • Use C79.89 for Secondary malignant neoplasm of other specified sites

  • Use C79.9 for Secondary malignant neoplasm of unspecified site

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to C79: its own notes plus those printed at 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.

  • secondary carcinoid tumors (C7B.-)
  • secondary neuroendocrine tumors (C7B.-)

Notes

General instructions on how these codes are used.

From Chapter 2 (C00-D49) Neoplasms applies to 1,730 codes
  • 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, its category, or a range that includes it.

Applicable To 2

These notes mention C79.

  • Z85.8 Personal history of malignant neoplasms of other organs and systems
    Conditions classifiable to C00-C14, C40-C49, C69-C75, C7A.098, C76-C79 names C76-C79, which includes this code
  • Z85.89 Personal history of malignant neoplasm of other organs and systems
    Conditions classifiable to C7A.098, C76, C77-C79 names C77-C79, which includes this code

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Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About C79Overview

What is the ICD-10 code for secondary malignant neoplasm of other and unspecified sites?

C79 is the ICD-10-CM category for secondary malignant neoplasm of other and unspecified sites, but it is a non-billable header: claims need a more specific code from this category, listed on this page.

Is C79 (Secondary malignant neoplasm of other and unspecified sites) a billable code?

No. This is a category header that groups the codes for secondary malignant neoplasm of other and unspecified sites, and headers cannot be submitted on claims. Claims for secondary malignant neoplasm of other and unspecified sites need a more specific code from this category, such as C79.00, C79.01, and C79.02.

Can C79 be reported with a code from C7B?

Not as a rule. The Excludes1 note on C79 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).