In simple words: This code indicates that cancer has spread to the small intestine from another part of the body where it originally started.

This code represents the presence of a secondary malignant neoplasm (cancer) that has spread to the small intestine from a primary cancer site located elsewhere in the body.

Example 1: A patient with a history of breast cancer presents with abdominal pain and weight loss. Imaging reveals a mass in the small intestine, confirmed by biopsy as metastatic breast cancer. C78.4 would be used to code the metastatic tumor in the small intestine., A patient with melanoma undergoes a PET scan that shows spread of the cancer to multiple sites, including the small intestine. Code C78.4 would be used in conjunction with the appropriate melanoma code., A patient with colon cancer develops symptoms suggestive of intestinal obstruction.A CT scan reveals a metastatic tumor in the small intestine, causing the obstruction.C78.4 would be assigned to code this secondary malignancy, along with the primary colon cancer code.

Documentation should clearly indicate the primary site of the cancer and the confirmation of metastasis to the small intestine. Imaging reports, biopsy results, and clinical findings should be documented.If functional activity is associated with the neoplasm, an additional code from Chapter 4 may be used.

** This code describes a secondary malignancy, meaning it originated elsewhere and spread to the small intestine.It's important to accurately code the primary site of the cancer as well.This information is crucial for treatment planning, prognosis, and research.