Billable / Specific Code
ICD-10-CM C79.9 is the diagnosis code for Secondary malignant neoplasm of unspecified site. This code falls under the section "Malignant neoplasms of ill-defined, other secondary and unspecified sites" within Chapter 2 — Neoplasms (C00-D49). It is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes. Medical coders and healthcare providers use this code to document and classify diagnoses in electronic health records, insurance claims, and clinical databases.
The following conditions should never be coded at the same time as C79.9. They are mutually exclusive:
Understanding where C79.9 sits in the ICD-10-CM classification helps ensure proper coding:
Yes, C79.9 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
C79.9 is the ICD-10-CM diagnosis code for "Secondary malignant neoplasm of unspecified site". It is used by healthcare providers to classify and document this condition in medical records and insurance claims.
The parent code of C79.9 is C79 ("Secondary malignant neoplasm of other and unspecified sites"). C79.9 provides a more specific classification within this category.
C79.9 is located in Section C76-C80 — "Malignant neoplasms of ill-defined, other secondary and unspecified sites" within Chapter 2 of the ICD-10-CM Tabular List.
Use C79.9 when the patients documented diagnosis matches "Secondary malignant neoplasm of unspecified site" and the clinical documentation supports this level of specificity. Always verify with the latest ICD-10-CM guidelines and payer requirements.
The ICD-10-CM code for Secondary malignant neoplasm of unspecified site is C79.9.
Yes, C79.9 can be used as a primary diagnosis code since it is billable and specific.
C79.9 is in Chapter 2 of the ICD-10-CM Tabular List.
Type 1 Excludes for C79.9 include: carcinomatosis NOS (C80.0); generalized cancer NOS (C80.0); malignant (primary) neoplasm of unspecified site (C80.1).
Yes, C79.9 is a valid ICD-10-CM code for the 2026 fiscal year, subject to official CMS updates.