ICD-10 Code C80 – Malignant neoplasm without specification of site (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C80 – Malignant neoplasm without specification of site
What it is
C80 is used when a malignant neoplasm is documented, but the primary site is not specified. It identifies cancer when the record does not name an organ or tissue of origin.
Clinical signs
Clinical features vary; refer to documentation. The diagnosis may be based on pathology, imaging, or an oncology note that confirms malignancy without identifying the site.
When to use this code
Use C80 when the provider confirms a malignant neoplasm and the chart does not state the primary site. It may apply at an initial encounter, during referral, or when records remain incomplete. If later documentation identifies the site, code the more specific site instead.
Do not use for
Do not use C80 if the primary site is known, even if the exact laterality or extent is unclear. Do not use it for suspected cancer without confirmation; check documentation for the final diagnosis.
Coding tip
Review pathology, imaging, and oncology notes carefully; if the site is documented anywhere in the record, assign the specific site code.