C26.9 Malignant neoplasm of ill-defined sites within the digestive system

The ICD-10-CM code for Malignant neoplasm of ill-defined sites within the digestive system is C26.9 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

2: Neoplasms (C00-D49)

Section

C15-C26: Malignant neoplasms of digestive organs (C15-C26)

Category C26

4 codes (3 billable)

FY2026 Status

Stable since FY2024

Inclusion Terms

• Malignant neoplasm of alimentary canal or tract NOS
• Malignant neoplasm of gastrointestinal tract NOS

U.S. Hospital Utilization

• An estimated 2,010 U.S. inpatient stays in 2023 included C26.9 among the documented diagnoses.
• 420 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

Tx of primary site (TOC entry)

a. Admission/Encounter for treatment of primary site ............................................................. 33

Tx of secondary site (TOC entry)

b. Admission/Encounter for treatment of secondary site .......................................................... 33

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)