ICD-10-CM 2027 diagnosis code
C78.4Secondary malignant neoplasm of small intestine
C78.4 is a valid, billable ICD-10-CM code for secondary malignant neoplasm of small intestine. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.
Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About C78.4
C78.4 is the ICD-10-CM diagnosis code for secondary malignant neoplasm of small intestine. It belongs to category C78 (secondary malignant neoplasm of respiratory and digestive organs), block C76-C80 (malignant neoplasms of ill-defined, other secondary and unspecified sites) and chapter 2 (neoplasms). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.
Within C78 (secondary malignant neoplasm of respiratory and digestive organs), C78.4 is specifically for secondary malignant neoplasm of small intestine. Related codes cover lung (C78.0), mediastinum (C78.1), pleura (C78.2), other and unspecified respiratory organs (C78.3), large intestine and rectum (C78.5), retroperitoneum and peritoneum (C78.6), liver and intrahepatic bile duct (C78.7) and other and unspecified digestive organs (C78.8).
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
In MS-DRG v44.0, it is part of the grouping logic for DRG 374 (Digestive Malignancy with MCC, relative weight 2.1109), DRG 375 (Digestive Malignancy with CC, relative weight 1.1838) and DRG 376 (Digestive Malignancy without CC/MCC, relative weight 0.8929), in MDC 06 (Diseases and Disorders of the Digestive System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
Before ICD-10, this condition was coded in ICD-9-CM as 197.4 (secondary malignant neoplasm of small intestine including duodenum).
Notes that apply from higher levels
Instructions written at a parent level also apply to C78.4.
Broader instructions also apply from Chapter 2: Neoplasms.
Table of Drugs & Neoplasms entries
- Neoplasm, neoplastic › duodenojejunal junction — Malignant Secondary
- Neoplasm, neoplastic › duodenum — Malignant Secondary
- Neoplasm, neoplastic › ileum — Malignant Secondary
- Neoplasm, neoplastic › intestine, intestinal › small — Malignant Secondary
- Neoplasm, neoplastic › intestine, intestinal › small › duodenum — Malignant Secondary
- Neoplasm, neoplastic › intestine, intestinal › small › ileum — Malignant Secondary
- Neoplasm, neoplastic › intestine, intestinal › small › jejunum — Malignant Secondary
- Neoplasm, neoplastic › jejunum — Malignant Secondary
- Neoplasm, neoplastic › Meckel diverticulum, malignant — Malignant Secondary
MS-DRG v44.0 grouping
All DRGs →Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.
MDC 06 · Diseases and Disorders of the Digestive System
ICD-9-CM equivalent
Converter →- 197.4Secondary malignant neoplasm of small intestine including duodenumexact
From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about C78.4
Is C78.4 billable?
- Yes. C78.4 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can C78.4 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict C78.4 as a principal diagnosis.
Is C78.4 a CC or MCC?
- C78.4 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.
What DRG does C78.4 group to?
- C78.4 is used in the MS-DRG v44.0 logic for MS-DRG 374 (Digestive Malignancy with MCC), MS-DRG 375 (Digestive Malignancy with CC) and MS-DRG 376 (Digestive Malignancy without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.
What is the ICD-9 code for C78.4?
- The CMS General Equivalence Mappings map C78.4 to ICD-9-CM 197.4.