What is ICD-10 code C17.3?

C17.3 is the ICD-10-CM diagnosis code for Meckel's diverticulum, malignant. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C17.3 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C17.3 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. C17.3 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. C17.3 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does C17.3 map to under V28?

C17.3 maps to CMS-HCC V28 HCC 20 (Lung and Other Severe Cancers). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

2026 ICD-10-CM C17.3: Meckel's diverticulum

C17.3 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

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Code lookupC17.3

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

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

C17.3

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

Meckel's diverticulum, malignant

This is a rare cancer that develops in Meckel's diverticulum, which is a small pouch-like remnant of tissue in the small intestine that some people are born with. The malignant tumor in this location requires specific coding to identify both the cancer and its unusual site.

Buddy Insight

Malignant Meckel diverticulum is an extremely rare cancer arising in a congenital remnant of the omphalomesenteric duct in the small intestine.

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 20

Lung and Other Severe Cancers

Code-level coefficient reference

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 C17.3Meckel's diverticulum, malignant

Inclusion Terms

Official

No inclusion terms are included in this display for C17.3. 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 C17.8Malignant neoplasm of overlapping sites of small intestine C17.9Malignant neoplasm of small intestine, unspecified

Includes

Official

No Includes notes are included in this display for C17.3. Check the code and parent instructions in the Code Book.

Excludes 1

Official

Meckel's diverticulum, congenital (Q43.0)
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 C17.3. Check the code and parent instructions in the Code Book.

Use Additional

Official

No Use Additional Code instructions are included in this display for C17.3. Check the code and parent instructions in the Code Book.

Code Also

Official

No Code Also instructions are included in this display for C17.3. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Documentation confirming both the presence of Meckel diverticulum and malignancy within it

Histological type of the malignancy (carcinoid, adenocarcinoma, sarcoma)

Pathological confirmation of malignancy (not just presence of Meckel diverticulum)

Stage of disease and extent of surgical resection

MEAT Support

HCC Buddy guidance

Documentation confirming both the presence of Meckel diverticulum and malignancy within it

Histological type of the malignancy (carcinoid, adenocarcinoma, sarcoma)

Pathological confirmation of malignancy (not just presence of Meckel diverticulum)

Stage of disease and extent of surgical resection

Audit Caution

HCC Buddy guidance

Coding benign Meckel diverticulum (Q43.0) as malignant without pathological confirmation of cancer

Using C17.2 (ileum) when the tumor specifically arises within the Meckel diverticulum

Missing this rare diagnosis because the coder is unfamiliar with Meckel diverticulum as a site for malignancy

Common Mistakes

HCC Buddy guidance

Q43.0 — Meckel diverticulum (displaced/persistent): congenital anomaly without malignancy; do not confuse benign with malignant

C17.2 — Malignant neoplasm of ileum: if the tumor is in the ileum near but not within a Meckel diverticulum, use ileum code

C17.8 — Overlapping sites of small intestine: if the tumor extends beyond the diverticulum into the ileum

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 C17.3 an HCC code?

Yes. C17.3 (Meckel's diverticulum, malignant) 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: C17.3 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: C17.3
Description: Meckel's diverticulum, malignant
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 C17.3 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for C17.3

For C17.3, 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

C17.3 is the ICD-10-CM diagnosis code for meckel's diverticulum, malignant. This is a rare cancer that develops in Meckel's diverticulum, which is a small pouch-like remnant of tissue in the small intestine that some people are born with. The malignant tumor in this location requires specific coding to identify both the cancer and its unusual site. C17.3 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, C17.3 maps to Lung and Other Severe Cancers (HCC 20) with a source-labeled community, non-dual, aged reference coefficient of 1.136. No V24 mapping is shown for C17.3; use the applicable model and payment year when reviewing the V28 mapping. 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.

Verify documentation confirms malignancy in Meckel's diverticulum specifically, as this is a rare condition; do not confuse with benign Meckel's diverticulum (Q43.0). For C17.3, 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 C17.3 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Verify documentation confirms malignancy in Meckel's diverticulum specifically, as this is a rare condition; do not confuse with benign Meckel's diverticulum (Q43.0)
•Ensure the histological type of the malignancy is documented separately if available, as additional codes may be needed to specify the cancer type (e.g., carcinoid, adenocarcinoma)

Clinical Significance

Malignant Meckel diverticulum is an extremely rare cancer arising in a congenital remnant of the omphalomesenteric duct in the small intestine. This code is uniquely specific because it identifies both the malignant nature and the unusual anatomical origin. The rarity of this diagnosis makes accurate coding critical, as it affects both clinical research data and appropriate risk adjustment for an uncommon condition requiring complex surgical management.

Documentation Requirements

✓Documentation confirming both the presence of Meckel diverticulum and malignancy within it
✓Histological type of the malignancy (carcinoid, adenocarcinoma, sarcoma)
✓Pathological confirmation of malignancy (not just presence of Meckel diverticulum)
✓Stage of disease and extent of surgical resection
✓Distinction from benign Meckel diverticulum

Excludes 1, Do NOT code together

Meckel's diverticulum, congenital (Q43.0)

Commonly Confused Codes

•Q43.0: Meckel diverticulum (displaced/persistent): congenital anomaly without malignancy; do not confuse benign with malignant
•C17.2: Malignant neoplasm of ileum: if the tumor is in the ileum near but not within a Meckel diverticulum, use ileum code
•C17.8: Overlapping sites of small intestine: if the tumor extends beyond the diverticulum into the ileum