All ICD10 Codes
C79Not billable, use a more specific code below

Secondary malignant neoplasm of other and unspecified sites

In Malignant neoplasms of ill-defined, other secondary and unspecified sites (C76-C80), chapter 2: Neoplasms

25 billable codes under C79: all are a CC; 24 map to HCC 18 (Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid), HCC 17 (Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic).A CC or MCC (major CC) is a secondary diagnosis that raises the MS-DRG payment. An HCC counts toward a Medicare Advantage patient's risk score.

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Instructional notes

Excludes1: not coded here, use a different code

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

Official coding guidelines

From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.

Rules for coding benign and malignant neoplasms: using the Neoplasm Table, sequencing primary and secondary sites, treatment encounters, complications, and current cancer versus personal history.

Read Section I.C.2 (page 32), 12 more topics

All codes under C79

C79 can't be used on a claim. Pick a billable code below; grey headings group them.

C79 MS-DRGs

As the principal diagnosis, the billable codes under C79 group to these 30 MS-DRGs (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.

Other codes that refer to C79

Notes on these codes point to C79.

  • Z80.8 Includes: Conditions classifiable to C00-C14, C40-C49, C69-C79
  • Z85.8 Includes: Conditions classifiable to C00-C14, C40-C49, C69-C75, C7A.098, C76-C79
  • Z85.89 Includes: Conditions classifiable to C7A.098, C76, C77-C79

About the condition

Plain-language background from MedlinePlus (National Library of Medicine), not coding guidance.

Cancer

Cancer is not just one disease but many diseases. Cancer begins in your cells, which are the building blocks of your body. Usually, your body forms new cells as needed, replacing old cells that die. Sometimes this process goes wrong. New cells grow even when you don't need them, and old cells don't die when they should. These extra cells can form a mass called a tumor.

Read more about cancer on MedlinePlus

Code history

Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.