C80.1 Malignant (primary) neoplasm, unspecified
The ICD-10-CM code for Malignant (primary) neoplasm, unspecified is C80.1 (FY2026). It is a billable, claim-ready diagnosis code.
Classification
- Chapter
- 2: Neoplasms (C00-D49)
- Section
- C76-C80: Malignant neoplasms of ill-defined, other secondary and unspecified sites (C76-C80)
- Category C80
- 4 codes (3 billable)
- FY2026 Status
- Stable since FY2024
Also Known As
ICD-10-CM Alphabetic Index entries that lead to C80.1:
- Tumor › malignant
- Cancer › unspecified site (primary)
- Carcinoma (malignant) › unspecified site (primary)
- Malignancy › unspecified site (primary)
- Sarcomatosis › unspecified site
- Tumor › malignant › mixed NEC
- Tumor › malignant › giant cell (type)
- Tumor › malignant › fusiform cell (type)
Inclusion Terms
- Cancer NOS
- Cancer unspecified site (primary)
- Carcinoma unspecified site (primary)
- Malignancy unspecified site (primary)
U.S. Hospital Utilization
- An estimated 29,735 U.S. inpatient stays in 2023 included C80.1 among the documented diagnoses.
- 2,260 stays listed it as the principal diagnosis.
Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.
Official Coding Guidelines
C80.1 malignant (primary) neoplasm unspecified—rare inpatient usek. Malignant neoplasm without specification of site Code C80.1, Malignant (primary) neoplasm, unspecified, equates to Cancer, unspecified. This code should only be used when no determination can be made as to the primary site of a malignancy. This code should rarely be used in the inpatient setting.
Tx of primary site (TOC entry)a. Admission/Encounter for treatment of primary site ............................................................. 33
Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026