C79.9

C79.9: Secondary malignant neoplasm of unspecified site

Billable / specific codeICD-10-CM

C79.9 is a billable, specific ICD-10-CM code for secondary malignant neoplasm of unspecified site. It is valid for submission on a claim.

Check C79.9 with the rest of the claim: free scrubber

Excludes1: never code together

These conditions cannot occur together. Billing both on the same encounter is a denial.

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

Inclusion terms

Alternative wordings a physician may use in the chart for this same code.

Metastatic cancer NOS
Metastatic disease NOS

Excludes1 inherited from the categories above C79.9

A category’s note binds every code beneath it.

Written on C79: Secondary malignant neoplasm of other and unspecified sites

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

Other codes that can never be billed with C79.9

Their own Excludes1 notes name this code, so the conflict is not listed above.

C80.1Malignant (primary) neoplasm, unspecified

Risk adjustment

C79.9 risk-adjusts. Under the CMS-HCC V28 model it maps to this category:

HCC 18 Cancer Metastatic to Bone, Other and Unspecified Metastatic Cancer; Acute Leukemia Except Myeloid2.341 RAF

Coefficient shown for the Community Non-dual Aged segment. A higher HCC in the same hierarchy will suppress this one, so capturing it does not always add score. Look up the whole chart to see which of its HCCs the hierarchy would zero.

Medicare coverage

C79.9 is named in 25 Medicare coverage policies: 25 listing it as supporting medical necessity. Which one applies depends on your Medicare contractor.

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