ICD-10 Code C18.2 – Malignant neoplasm of ascending colon (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code C18.2 – Malignant neoplasm of ascending colon
What it is
C18.2 identifies a malignant tumor arising in the ascending colon, the first part of the large intestine on the right side. Use it when documentation specifies primary cancer of the ascending colon.
Clinical signs
Clinical features vary; refer to documentation. Commonly reported findings include a confirmed colon mass, biopsy-proven adenocarcinoma, or imaging and endoscopic evidence consistent with malignancy in the ascending colon.
When to use this code
Use C18.2 when the provider documents primary malignant neoplasm of the ascending colon, including cases confirmed by colonoscopy, pathology, or surgical report. You may also use it when the record clearly localizes the cancer to the ascending colon. If the site is described only as colon cancer without a more specific location, check documentation.
Do not use for
Do not use this code for benign polyps, carcinoma in situ, or malignancies of other colon segments. If the documentation does not specify the ascending colon, do not assume this code.
Coding tip
Code the most specific colon site documented; verify pathology or operative notes before assigning C18.2.