C79.9: Secondary malignant neoplasm of unspecified site

Clinical notes

Excludes1 (not coded here)

An Excludes1 note is a pure exclusion: the excluded condition and this code should never be reported together, because the two conditions cannot occur at the same time (e.g. a congenital form vs. an acquired form of the same disease).

carcinomatosis NOS (C80.0)
generalized cancer NOS (C80.0)
malignant (primary) neoplasm of unspecified site (C80.1)

Also known as

Alternate wording, synonyms, or specific conditions that fall under this code, listed to help confirm you've picked the right one.

Metastatic cancer NOS
Metastatic disease NOS

Documentation support

General coding-documentation guidance — not a substitute for payer-specific requirements or professional coding judgment.

•This code describes an unspecified presentation. If the medical record documents a more specific detail (e.g. laterality, type, or affected site), a more specific sibling code should be used instead — see Related codes below.
•Confirm the excluded condition(s) listed above are not also present — Excludes1 conditions cannot be coded together with this one.
•As a general rule, code to the highest level of specificity supported by the documentation in the medical record.

Related codes in this category

ICD-9-CM equivalent

Informational only — GEM mappings are approximate, not guaranteed one-to-one equivalents. Verify before use in billing.

19889Approximate match

View full ICD-10 → ICD-9 crosswalk →

Associated MS-DRGs

C79.9 can serve as the principal diagnosis for these Medicare Severity Diagnosis-Related Groups.

Informational only — actual DRG assignment also depends on procedures, complications/comorbidities (CC/MCC), discharge status, and payer-specific rules not reflected here.