2027 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
- Risk Adjusts — HCC 22
- 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 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 374 through 376. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Gastrointestinal cancers - all other types.
For Medicare Advantage risk adjustment, C26.9 maps to CMS-HCC Category 22 (Bladder, Colorectal, and Other Cancers) under the V28 model, adding a risk factor of about 0.363 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
C26.9 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
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
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to C26.9: its own notes plus those printed at C26, block C15-C26, and Chapter 2. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Malignant neoplasm of alimentary canal or tract NOS
- Malignant neoplasm of gastrointestinal tract NOS
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- malignant neoplasm of peritoneum and retroperitoneum (C48.-)
- Kaposi's sarcoma of gastrointestinal sites (C46.4)
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- gastrointestinal stromal tumors (C49.A-)
Notes
General instructions on how these codes are used.
- Functional activity
- All neoplasms are classified in this chapter, whether they are functionally active or not. An additional code from Chapter 4 may be used, to identify functional activity associated with any neoplasm.
- Morphology [Histology]
- Chapter 2 classifies neoplasms primarily by site (topography), with broad groupings for behavior, malignant, in situ, benign, etc. The Table of Neoplasms should be used to identify the correct topography code. In a few cases, such as for malignant melanoma and certain neuroendocrine tumors, the morphology (histologic type) is included in the category and codes.
- Primary malignant neoplasms overlapping site boundaries
- A primary malignant neoplasm that overlaps two or more contiguous (next to each other) sites should be classified to the subcategory/code .8 ('overlapping lesion'), unless the combination is specifically indexed elsewhere. For multiple neoplasms of the same site that are not contiguous, such as tumors in different quadrants of the same breast, codes for each site should be assigned.
- Malignant neoplasm of ectopic tissue
- Malignant neoplasms of ectopic tissue are to be coded to the site mentioned, e.g., ectopic pancreatic malignant neoplasms are coded to pancreas, unspecified (C25.9).
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name C26.9, its category, or a range that includes it.
Applicable To 1
These notes mention C26.9.
- Z80.0 Family history of malignant neoplasm of digestive organs
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 | – | – | – | – | – |
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Convert C26.9 to ICD-9-CMHistory
Code HistoryHistory
Questions About C26.9Overview
What is the ICD-10 code for 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 (sometimes written as C269). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
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, 2026 through September 30, 2027.
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 375, 374, 376, with relative weights from 0.8925 to 2.1101 depending on complications. Higher weights mean higher Medicare reimbursement.
Can C26.9 be reported with C76.2?
Not as a rule. The Excludes1 note on C26.9 lists "malignant neoplasm of abdominal NOS (C76.2)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
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.
What HCC is C26.9?
C26.9 (malignant neoplasm of ill-defined sites within the digestive system) maps to CMS-HCC Category 22 (Bladder, Colorectal, and Other Cancers), commonly written as HCC 22, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 11 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. It does not map to any RxHCC in the Part D prescription drug model.
Does C26.9 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, C26.9 adds a risk adjustment factor of about 0.363 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.314 to 0.410 depending on the payment segment). A more severe related category (HCC 17, HCC 18, HCC 19, HCC 20, and HCC 21) supersedes it when both are reported. See the full factor table on the HCC 22 category page.
