C17.2 ICD-10-CM Code: Malignant neoplasm of ileum
HCC Buddy Code Card
Digital ICD-10 code-book layout with official code detail, always-visible risk models, Code Trumping, and Buddy coding guidance.
FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of digestive organs (C15-C26)
C17.2
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceMalignant neoplasm of ileum
Cancer that develops in the ileum, which is the final and longest section of the small intestine.
Buddy Insight
Malignant neoplasm of the ileum affects the longest and most distal segment of the small intestine.
CMS-HCC V28
MappedHCC 20
RAF 0.0
CMS-HCC V24
MappedHCC 9
RAF 0.973
ACA/HHS
00
RAF 0
ESRD/PACE
MappedHCC 9
RAF 0.0
RXHCC
MappedHCC 22
RAF 0.0
Code Trumping
Basket needed
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for C17.2 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for C17.2 in this effective period.
Related Child Codes
Includes
OfficialICD-10-CM does not list Includes notes for C17.2 in this effective period.
Excludes 1
Official- malignant neoplasm of ileocecal valve (C18.0)
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for C17.2 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for C17.2 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for C17.2 in this effective period.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is C17.2 an HCC code?
Yes. C17.2 maps to Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model (and Lung and Other Severe Cancers under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for C17.2
For C17.2to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.
- 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
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed C17.2 during that encounter, not just copy-forwarded from a problem list.
What This Code Means
C17.2 is the ICD-10-CM diagnosis code for malignant neoplasm of ileum. Cancer that develops in the ileum, which is the final and longest section of the small intestine. C17.2 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, C17.2 maps to Lung and Other Severe Cancers (HCC 20) with a community, non-dual, aged base RAF weight of 0.000. Under the older V24 model, C17.2 mapped to the same category but with a base RAF weight of 0.973, V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Document whether this is primary ileal cancer or secondary involvement; ileal cancers are uncommon. Because C17.2 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. 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, RAF weights, and MEAT documentation criteria for C17.2 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Document whether this is primary ileal cancer or secondary involvement; ileal cancers are uncommon
- •Note any association with Crohn's disease or other predisposing conditions if present
Clinical Significance
Malignant neoplasm of the ileum affects the longest and most distal segment of the small intestine. The ileum is a relatively common site for carcinoid (neuroendocrine) tumors and lymphoma compared to other small bowel segments. Ileal cancers may present with obstruction, intussusception, or bleeding, and patients with Crohn disease affecting the ileum have an increased risk of malignancy. Accurate coding ensures risk adjustment reflects the complex care these patients require.
Documentation Requirements
- ✓Confirmed ileal location as the primary malignant site
- ✓Histological type (neuroendocrine/carcinoid tumors are common in this location)
- ✓Any history of Crohn disease or other predisposing inflammatory conditions
- ✓Stage of disease including mesenteric lymph node involvement
- ✓Distinction from Meckel diverticulum malignancy (C17.3)
Excludes 1, Do NOT code together
- malignant neoplasm of ileocecal valve (C18.0)
Commonly Confused Codes
- •C17.1 — Jejunum: adjacent segment; boundary may be difficult to determine radiologically
- •C17.3 — Meckel diverticulum, malignant: if cancer arises in Meckel diverticulum specifically, use C17.3 rather than C17.2
- •C18.0 — Cecum: the terminal ileum connects to the cecum; ensure primary site is ileum not cecum
- •C7A.012 — Malignant carcinoid tumor of ileum: carcinoid tumors of the ileum have their own specific code