2027 ICD-10-CM Diagnosis Code C24.1Malignant neoplasm of ampulla of Vater
ICD-10-CM Codes›C00–D49›C15-C26›C24
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 20
- Chronic Condition
C24.1 is a billable ICD-10-CM diagnosis code for malignant neoplasm of ampulla of Vater. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 435 through 437. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 21 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Gastrointestinal cancers - all other types.
For Medicare Advantage risk adjustment, C24.1 maps to CMS-HCC Category 20 (Lung and Other Severe Cancers) under the V28 model, adding a risk factor of about 1.136 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
C24.1 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.
- Adenocarcinoma of duodenum
- Adenocarcinoma of small intestine
- Carcinoma common bile duct
- Carcinoma of ampulla of Vater
- Carcinoma of duodenum
- Carcinoma of extrahepatic bile duct
- Malignant neoplasm of ampulla of Vater
- Pancreatic ductal adenocarcinoma
- Primary adenocarcinoma of ampulla of Vater
- Primary adenocarcinoma of bile duct
- Primary adenocarcinoma of common bile duct
- Primary adenocarcinoma of pancreas
- Primary adenocarcinoma of pancreatic duct
- Primary adenocarcinoma of small intestine
- Primary carcinoma common bile duct
- Primary carcinoma liver and/or biliary system
- Primary carcinoma of ampulla of Vater
- Primary carcinoma of bile duct
- Primary carcinoma of duodenum
- Primary carcinoma of extrahepatic bile duct
- Primary carcinoma of pancreas
- Primary malignant neoplasm of ampulla of Vater
- Primary malignant neoplasm of common bile duct
- Primary malignant neoplasm of duodenum
- Primary malignant neoplasm of pancreatic duct
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to C24.1: its own notes plus those printed at C24, block C15-C26, and Chapter 2. A note printed at a category, block or chapter applies to every code under it.
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- malignant neoplasm of intrahepatic bile duct (C22.1)
- 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 C24.1, its category, or a range that includes it.
Applicable To 1
These notes mention C24.1.
- Z80.0 Family history of malignant neoplasm of digestive organs
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Malignant Ampulla of Vater Neoplasm
a primary or metastatic malignant neoplasm involving the ampulla of vater.
Table of NeoplasmsClinical
Patient EducationClinical
Bile Duct Cancer
Your liver makes a digestive juice called bile. Your gallbladder stores it between meals. When you eat, your gallbladder pushes the bile into tubes called bile ducts. They carry the bile to your small intestine. The bile helps break down fat. It also helps the liver get rid of toxins and wastes.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert C24.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About C24.1Overview
What is the ICD-10 code for malignant neoplasm of ampulla of Vater?
The ICD-10-CM code for malignant neoplasm of ampulla of Vater is C24.1 (sometimes written as C241). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is C24.1 a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report malignant neoplasm of ampulla of Vater on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does C24.1 group to?
When malignant neoplasm of ampulla of Vater is the principal diagnosis on an inpatient stay, it groups to MS-DRG 436, 437, 435, with relative weights from 0.8078 to 1.8428 depending on complications. Higher weights mean higher Medicare reimbursement.
Is C24.1 a CC or MCC?
CMS lists C24.1 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 21 closely related codes in its exclusion list.
Can C24.1 be reported with C22.1?
Not as a rule. The Excludes1 note at C24, which applies to C24.1, lists "malignant neoplasm of intrahepatic bile duct (C22.1)". 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 HCC is C24.1?
C24.1 (malignant neoplasm of ampulla of Vater) maps to CMS-HCC Category 20 (Lung and Other Severe Cancers), commonly written as HCC 20, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 9 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 22.
Does C24.1 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, C24.1 adds a risk adjustment factor of about 1.136 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.672 to 1.214 depending on the payment segment). A more severe related category (HCC 17, HCC 18, and HCC 19) supersedes it when both are reported. See the full factor table on the HCC 20 category page.
