ICD-10 Code C26.9 – Malignant neoplasm of ill-defined sites within the digestive system (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C26.9 – Malignant neoplasm of ill-defined sites within the digestive system
What it is
C26.9 identifies a malignant tumor in the digestive system when the exact site is not specified or is poorly defined. Use it only when documentation confirms a digestive tract cancer but does not name a more precise location.
Clinical signs
Clinical features vary; refer to documentation. Patients may have nonspecific gastrointestinal symptoms, but the code is based on the documented diagnosis and site uncertainty, not on symptoms alone.
When to use this code
Use this code when the record states a primary malignant neoplasm involving an ill-defined digestive site and no more specific anatomic site is documented. It may also fit when pathology or imaging confirms malignancy, but the exact origin within the digestive system remains unclear. Check documentation before assigning it if a more specific code is available.
Do not use for
Do not use C26.9 if the cancer site is known and documented elsewhere in the digestive system. Do not assign it for benign, uncertain, or metastatic disease without confirmation of a primary malignant neoplasm.
Coding tip
Always look for a more specific digestive-site code before defaulting to C26.9.