2026 ICD-10-CM Diagnosis Code C26.9Malignant neoplasm of ill-defined sites within the digestive system
ICD-10-CM Codes›C00–D49›C15-C26›C26
- Billable — Valid for Submission
- Chronic Condition
C26.9 is a billable ICD-10-CM diagnosis code for malignant neoplasm of ill-defined sites within the digestive system. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 374 through 376. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Gastrointestinal cancers - all other types.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Malignant neoplasm of digestive organ
- Malignant neoplasm of digestive system
- Malignant neoplasm of gastrointestinal tract
- Malignant neoplasm of lower gastrointestinal tract
- Malignant neoplasm of overlapping sites of digestive system
- Malignant neoplasm of upper gastrointestinal tract
- Mucinous adenocarcinoma of gastrointestinal tract
- Overlapping malignant neoplasm of gastrointestinal tract
- Primary adenocarcinoma of digestive organ
- Primary adenocarcinoma of gastrointestinal tract
- Primary malignant neoplasm of gastrointestinal tract
- Primary mucinous adenocarcinoma of gastrointestinal tract
- Primary mucinous carcinoma of digestive organ
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- Malignant neoplasm of alimentary canal or tract NOS
- Malignant neoplasm of gastrointestinal tract NOS
Type 1 Excludes
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Table of NeoplasmsClinical
Anatomical sites in the Table of Neoplasms that reference this code family.
| Site | Malig. Primary | Malig. Secondary | Ca in situ | Benign | Uncertain | Unspec. |
|---|---|---|---|---|---|---|
| alimentary canal or tract NEC | C26.9 | C78.80 | D01.9 | D13.99 | D37.9 | D49.0 |
| digestive organs, system, tube, or tract NEC | C26.9 | C78.89 | D01.9 | D13.99 | D37.9 | D49.0 |
| gastrocolic | C26.9 | C78.89 | D01.9 | D13.99 | D37.9 | D49.0 |
| gastrointestinal (tract) NEC | C26.9 | C78.89 | D01.9 | D13.99 | D37.9 | D49.0 |
| peritoneum, peritoneal (cavity) › overlapping lesion › with digestive organs | C26.9 | – | – | – | – | – |
Patient EducationClinical
Cancer
Cancer is not just one disease but many diseases. Cancer begins in your cells, which are the building blocks of your body. Usually, your body forms new cells as needed, replacing old cells that die. Sometimes this process goes wrong. New cells grow even when you don't need them, and old cells don't die when they should.
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Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert C26.9 to ICD-9-CMHistory
Code HistoryHistory
Questions About C26.9Overview
Is C26.9 (Malignant neoplasm of other and ill-defined digestive organs) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report malignant neoplasm of ill-defined sites within the digestive system on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does C26.9 group to?
When malignant neoplasm of ill-defined sites within the digestive system is the principal diagnosis on an inpatient stay, it groups to MS-DRG 374, 375, 376, with relative weights from 0.9243 to 2.1387 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of C26.9?
Under the General Equivalence Mappings, malignant neoplasm of ill-defined sites within the digestive system converts to ICD-9-CM 159.8 (mal neo gi/intra-abd NEC) and 159.9 (mal neo GI tract ill-def). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:
- The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
- The condition places limitations on self-care, independent living, and social interactions.
