ICD-10 Code C17.8 – Malignant neoplasm of overlapping sites of small intestine (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C17.8 – Malignant neoplasm of overlapping sites of small intestine
What it is
This code identifies a malignant tumor of the small intestine that spans two or more adjacent sites and cannot be assigned to one specific subsite. Use it when the documentation states overlap or crossing of small-intestine locations.
Clinical signs
Clinical features vary; refer to documentation. Commonly documented findings may include abdominal pain, weight loss, anemia, bleeding, or bowel obstruction, but the diagnosis should be based on the recorded site and malignancy.
When to use this code
Use C17.8 when the provider documents a primary cancer involving overlapping areas of the small intestine, such as a lesion crossing borders between adjacent segments. Code it when the record does not support a single more specific small-intestine site. If the note is unclear, check documentation before assigning a code.
Do not use for
Do not use this code for a malignant neoplasm clearly limited to one small-intestine subsite, such as duodenum, jejunum, or ileum. Do not use it for benign tumors or secondary metastatic disease unless the documentation specifically supports C17.8.
Coding tip
Review operative, pathology, and imaging reports for exact anatomic wording before choosing an overlapping-site code.