2026 ICD-10-CM Diagnosis Code C78.4Secondary malignant neoplasm of small intestine

ICD-10-CM Codes›C00–D49›C76-C80›C78

ICD-10-CM C78.4
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

C78.4 is a billable ICD-10-CM diagnosis code for secondary malignant neoplasm of small intestine. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 374 through 376. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Secondary malignancies.

Code Identity

ICD-10-CM Code
C78.4
Billable Status
Yes — Valid for Submission
Code Describes
Secondary malignant neoplasm of small intestine
Short Description
Secondary malignant neoplasm of small intestine
Same as the full description in the CMS dataset.
Parent Code
C78
Secondary malignant neoplasm of respiratory and digestive organs

Code Classification

ChapterC00–D49Neoplasms
SectionC76-C80Malignant neoplasms of ill-defined, other secondary and unspecified sites
CategoryC78Secondary malignant neoplasm of respiratory and digestive organs
This CodeC78.4Secondary malignant neoplasm of small intestine

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Adenocarcinoma of Meckel diverticulum
  • Adenocarcinoma of small intestine
  • Malignant neoplasm of ileum
  • Malignant neoplasm of jejunum
  • Malignant neoplasm of Meckel's diverticulum
  • Metastatic adenocarcinoma to Meckel diverticulum
  • Metastatic carcinoma to duodenum
  • Metastatic malignant neoplasm to duodenum
  • Metastatic malignant neoplasm to ileum
  • Metastatic malignant neoplasm to jejunum
  • Metastatic malignant neoplasm to Meckel's diverticulum
  • Metastatic malignant neoplasm to small intestine
  • Metastatic squamous cell carcinoma to small intestine
  • Neoplasm of Meckel's diverticulum
  • Squamous cell carcinoma of small intestine
  • Tumor invades beyond pancreatic capsule to adjacent structures AND/OR organs
  • Tumor invades beyond pancreatic capsule to duodenum

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NEO070
Secondary malignancies
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Duodenal Neoplasms

    tumors or cancer of the duodenum.

  • Duodenum

    the shortest and widest portion of the small intestine adjacent to the pylorus of the stomach. it is named for having the length equal to about the width of 12 fingers.

  • Jejunal Neoplasms

    tumors or cancer in the jejunum region of the small intestine (intestine, small).

  • Jejunum

    the middle portion of the small intestine, between duodenum and ileum. it represents about 2/5 of the remaining portion of the small intestine below duodenum.

Table of NeoplasmsClinical

Anatomical sites in the Table of Neoplasms that reference this code family.

SiteMalig.
Primary		Malig.
Secondary		Ca
in situ		BenignUncertainUnspec.
duodenojejunal junctionC17.8C78.4D01.49D13.39D37.2D49.0
duodenumC17.0C78.4D01.49D13.2D37.2D49.0
ileumC17.2C78.4D01.49D13.39D37.2D49.0
intestine, intestinal › smallC17.9C78.4D01.40D13.30D37.2D49.0
intestine, intestinal › small › duodenumC17.0C78.4D01.49D13.2D37.2D49.0
intestine, intestinal › small › ileumC17.2C78.4D01.49D13.39D37.2D49.0
intestine, intestinal › small › jejunumC17.1C78.4D01.49D13.39D37.2D49.0
jejunumC17.1C78.4D01.49D13.39D37.2D49.0
Meckel diverticulum, malignantC17.3C78.4D01.49D13.39D37.2D49.0

Patient EducationClinical

Intestinal Cancer

Your small intestine is part of your digestive system. It is a long tube that connects your stomach to your large intestine. Intestinal cancer is rare, but eating a high-fat diet or having Crohn's disease, celiac disease, or a history of colonic polyps can increase your risk.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert C78.4 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
197.4 Sec malig neo sm bowel
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About C78.4Overview

Is C78.4 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report secondary malignant neoplasm of small intestine on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does C78.4 group to?

When secondary malignant neoplasm of small intestine is the principal diagnosis on an inpatient stay, it groups to MS-DRG 374, 375, 376, with relative weights from 0.9243 to 2.1387 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of C78.4?

Under the General Equivalence Mappings, secondary malignant neoplasm of small intestine converts to ICD-9-CM 197.4 (sec malig neo sm bowel). The mapping is a direct match.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.