ICD-10 Code C78.4 – Secondary malignant neoplasm of small intestine (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C78.4 – Secondary malignant neoplasm of small intestine
What it is
This code identifies metastatic cancer in the small intestine, meaning a malignant tumor has spread there from another primary site. It does not describe a cancer that started in the small intestine.
Clinical signs
Clinical features vary; refer to documentation. Findings may include imaging or pathology evidence of metastatic involvement of the small intestine, with symptoms such as abdominal pain, obstruction, bleeding, or weight loss.
When to use this code
Use C78.4 when the record clearly states secondary malignant neoplasm of the small intestine or documents metastatic disease to that site. Apply it when the primary cancer is elsewhere and the small intestine involvement is confirmed or clinically established.
Use the code for inpatient, outpatient, or problem-list documentation when the provider identifies small-intestine metastasis. Check documentation if the note only says “GI metastases” or “abdominal metastases” without naming the small intestine.
Do not use for
Do not use this code for primary small-intestine cancer or for nonspecific abdominal spread without site confirmation. Check documentation if the record does not clearly distinguish primary from secondary malignancy.
Coding tip
Always code the primary malignancy first when documentation supports it, and verify the metastatic site is specifically the small intestine.