C78.4 ICD-10-CM Code: Secondary malignant neoplasm of small intestine
Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.
Inpatient Payment Groups (MS-DRG)
MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43.0 (FY2026), Appendix B.
- MS-DRG 374 — DIGESTIVE MALIGNANCY WITH MCC (MDC 06)
- MS-DRG 375 — DIGESTIVE MALIGNANCY WITH CC (MDC 06)
- MS-DRG 376 — DIGESTIVE MALIGNANCY WITHOUT CC/MCC (MDC 06)
A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.
Risk Adjustment (CMS-HCC)
Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.
- HCC 17 — Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic (supersedes HCC 18, HCC 19, HCC 20, HCC 21, HCC 22, HCC 23)
Other models: CMS-HCC V22 HCC 8 · RxHCC V08 HCC 20
Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.
Code Set: Valid FY2026 and FY2027. FY2026 took effect October 1, 2025.
Official Registry Overview & Definition
Official Tabular Instructional Notes
Sequencing, inclusion, and exclusion notes published for C78.4 in the official ICD-10-CM tabular list.
Excludes1 — Not Coded Here
Conditions that can never be reported with this code; the two are mutually exclusive.
- secondary carcinoid tumors of liver (C7B.02)
- secondary carcinoid tumors of peritoneum (C7B.04)
Excludes2 — Not Included Here
Conditions not covered by this code, but which may be reported alongside it when both are present.
- lymph node metastases (C77.0)
Nearest Codes in This Family
Official ICD-10-CM classifications closest to C78.4 in its code family, with their registry titles.
- C78.3 — Secondary malignant neoplasm of other and unspecified respiratory organs
- C78.30 — Secondary malignant neoplasm of unspecified respiratory organ
- C78.31 — Secondary malignant neoplasm of larynx
- C78.32 — Secondary malignant neoplasm of pharynx
- C78.39 — Secondary malignant neoplasm of other respiratory organs
- C78.5 — Secondary malignant neoplasm of large intestine and rectum
- C78.6 — Secondary malignant neoplasm of retroperitoneum and peritoneum
- C78.7 — Secondary malignant neoplasm of liver and intrahepatic bile duct
- C78.8 — Secondary malignant neoplasm of other and unspecified digestive organs
- C78.80 — Secondary malignant neoplasm of unspecified digestive organ
Neoplasm Table Sites (9)
Anatomical sites from the official ICD-10-CM Table of Neoplasms that map to this code, with the matching behavior column.
- 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