ICD-10-CM 2027
ICD-10 code for metastatic disease
Secondary malignant neoplasm of unspecified site
From the official ICD-10-CM alphabetic index entry “Disease, diseased › metastatic”. Page updated September 29, 2026.
About coding metastatic disease
The ICD-10-CM code for metastatic disease is C79.9 (Secondary malignant neoplasm of unspecified site).
Within C79, choose C79.9 (unspecified site) only when documentation doesn't support a more specific option: kidney and renal pelvis (C79.0), bladder and other and unspecified urinary organs (C79.1), skin (C79.2), brain and cerebral meninges (C79.3), other and unspecified parts of nervous system (C79.4), bone and bone marrow (C79.5), ovary (C79.6), adrenal gland (C79.7) and 1 more.
Don't report C79.9 together with the conditions in its Excludes1 note: carcinomatosis NOS (C80.0), generalized cancer NOS (C80.0) and malignant (primary) neoplasm of unspecified site (C80.1).
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
Don't confuse with (Excludes1 for C79.9)
Common questions about metastatic disease ICD-10 codes
What is the ICD-10 code for metastatic disease?
- C79.9 — Secondary malignant neoplasm of unspecified site.
Is C79.9 billable?
- Yes. C79.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can C79.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict C79.9 as a principal diagnosis.
Is C79.9 a CC or MCC?
- C79.9 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.