C17.9 maps to CMS-HCC V28 20. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC coding software

ICD-10-CM Code View

HCC Buddy Code Card

Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.

Code lookupC17.9

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of digestive organs (C15-C26)

C17.9

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Malignant neoplasm of small intestine, unspecified

This code represents cancer that has developed in the small intestine, but the specific location within the small intestine (duodenum, jejunum, or ileum) has not been identified or documented. It is used when a patient has been diagnosed with small intestine cancer without more specific anatomical detail.

Buddy Insight

Unspecified small intestine cancer is used when documentation confirms malignancy but does not identify which segment (duodenum, jejunum, or ileum) is involved.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 20

Lung and Other Severe Cancers

Coefficient HCC 20: 1.136 (Community Non-Dual Aged (CNA))

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 009

HHS-HCC 009 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 9

Lung and Other Severe Cancers

Code-level coefficient reference

RXHCC

Mapped

HCC 22

Prostate, Breast, Bladder, an...

Code-level coefficient reference

Code Book Path

Official

C17Malignant neoplasm of small intestine C17.9Malignant neoplasm of small intestine, unspecified

Inclusion Terms

Official

No inclusion terms are included in this display for C17.9. Check the code and parent instructions in the Code Book.

Excludes 2

Official

gastrointestinal stromal tumors (C49.A-)Inherited from C15-C26

Related Codes

Official

C17.0Malignant neoplasm of duodenum C17.1Malignant neoplasm of jejunum C17.2Malignant neoplasm of ileum C17.3Meckel's diverticulum, malignant C17.8Malignant neoplasm of overlapping sites of small intestine

Includes

Official

No Includes notes are included in this display for C17.9. Check the code and parent instructions in the Code Book.

Excludes 1

Official

Kaposi's sarcoma of gastrointestinal sites (C46.4)Inherited from C15-C26, C17
malignant carcinoid tumors of the small intestine (C7A.01)Inherited from C15-C26, C17

Code First

Official

No Code First sequencing instructions are included in this display for C17.9. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for C17.9. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for C17.9. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Confirmed malignancy of the small intestine

Review of all available records (pathology, operative notes, imaging) for segment identification before defaulting to unspecified

Histological type if known

Stage of disease

MEAT Support

HCC Buddy guidance

Confirmed malignancy of the small intestine

Review of all available records (pathology, operative notes, imaging) for segment identification before defaulting to unspecified

Histological type if known

Stage of disease

Audit Caution

HCC Buddy guidance

Defaulting to unspecified when operative or pathology reports identify the specific segment

Using this code for a tumor that is actually in the large intestine (C18-C20) due to confusion about anatomy

Not querying the provider when imaging shows the tumor location but the clinical note does not specify

Common Mistakes

HCC Buddy guidance

C17.0-C17.2 — Specific small intestine segments: always use the more specific code when documentation supports it

C17.8 — Overlapping sites: use when tumor is known to span multiple segments, not when location is unknown

C26.0 — Intestinal tract, part unspecified: even broader unspecified code; use C17.9 when small intestine is confirmed but segment is not

D37.2 — Neoplasm of uncertain behavior of small intestine: different behavior classification; confirm malignancy

Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →

Is C17.9 an HCC code?

Yes. C17.9 (Malignant neoplasm of small intestine, unspecified) maps to HCC 20, Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 1.136. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.

Coder answer: C17.9 is billable and maps to V28 HCC 20, Lung and Other Severe Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: C17.9
Description: Malignant neoplasm of small intestine, unspecified
HCC (V28): HCC 20 — Lung and Other Severe Cancers
RAF reference coefficient: 1.136
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 20, Lung and Other Severe Cancers

1.136

ESRDHCC 9, Lung and Other Severe Cancers

Not separately weighted

RxHCCHCC 22, Prostate, Breast, Bladder, and Other Cancers and Tumors

Not separately weighted

These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.

Work C17.9 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for C17.9

For C17.9, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.

MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
EEvaluate: test results, medication response, or physical findings reviewed by the provider
AAssess: explicit mention in the assessment or plan with acknowledgment of status
TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis

Coder workflow notes

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What This Code Means

C17.9 is the ICD-10-CM diagnosis code for malignant neoplasm of small intestine, unspecified. This code represents cancer that has developed in the small intestine, but the specific location within the small intestine (duodenum, jejunum, or ileum) has not been identified or documented. It is used when a patient has been diagnosed with small intestine cancer without more specific anatomical detail. C17.9 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of digestive organs (c15-c26).

Under the CMS-HCC V28 risk adjustment model, C17.9 maps to Lung and Other Severe Cancers (HCC 20) with a source-labeled community, non-dual, aged reference coefficient of 1.136. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.

Query the physician if the specific site of the small intestine cancer is documented in the medical record, as codes C17.0 (duodenum), C17.1 (jejunum), and C17.2 (ileum) provide more specificity and may affect treatment planning and staging. For C17.9, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.

HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for C17.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Query the physician if the specific site of the small intestine cancer is documented in the medical record, as codes C17.0 (duodenum), C17.1 (jejunum), and C17.2 (ileum) provide more specificity and may affect treatment planning and staging
•Ensure this code is used only when the site is truly unspecified; review pathology reports and imaging studies which often document the exact location of the malignancy

Clinical Significance

Unspecified small intestine cancer is used when documentation confirms malignancy but does not identify which segment (duodenum, jejunum, or ileum) is involved. Small bowel cancers are rare overall, accounting for less than 5% of gastrointestinal malignancies, but carry significant morbidity. While this code captures the appropriate HCC, documentation improvement efforts should aim to identify the specific segment from surgical, pathological, or imaging records.

Documentation Requirements

✓Confirmed malignancy of the small intestine
✓Review of all available records (pathology, operative notes, imaging) for segment identification before defaulting to unspecified
✓Histological type if known
✓Stage of disease
✓Treatment status

Commonly Confused Codes

•C17.0-C17.2: Specific small intestine segments: always use the more specific code when documentation supports it
•C17.8: Overlapping sites: use when tumor is known to span multiple segments, not when location is unknown
•C26.0: Intestinal tract, part unspecified: even broader unspecified code; use C17.9 when small intestine is confirmed but segment is not
•D37.2: Neoplasm of uncertain behavior of small intestine: different behavior classification; confirm malignancy