2026 ICD-10-CM Diagnosis Code C18.8Malignant neoplasm of overlapping sites of colon
ICD-10-CM Codes›C00–D49›C15-C26›C18
- Billable — Valid for Submission
- Chronic Condition
C18.8 is a billable ICD-10-CM diagnosis code for malignant neoplasm of overlapping sites of colon. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 374 through 376. Coders also document this condition as overlapping malignant neoplasm of colon. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Gastrointestinal cancers - colorectal.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Overlapping malignant neoplasm of colon
- Overlapping malignant neoplasm of colon and rectum
- Primary malignant neoplasm of overlapping sites of colon
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Table of NeoplasmsClinical
Anatomical sites in the Table of Neoplasms that reference this code family.
| Site | Malig. Primary | Malig. Secondary | Ca in situ | Benign | Uncertain | Unspec. |
|---|---|---|---|---|---|---|
| intestine, intestinal › large › colon › overlapping lesion | C18.8 | – | – | – | – | – |
| intestine, intestinal › large › overlapping lesion | C18.8 | – | – | – | – | – |
Patient EducationClinical
Colorectal Cancer
Colorectal cancer is cancer that develops in the tissues of the colon or rectum. Your colon and rectum are part of your digestive system:
The full article covers:
- What is colorectal cancer?
- What causes colorectal cancer?
- Who is more likely to develop colorectal cancer?
- What are the symptoms of colorectal cancer?
- What is screening for colorectal cancer and who needs it?
- How is colorectal cancer diagnosed?
- What are the treatments for colorectal cancer?
- Can colorectal cancer be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert C18.8 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About C18.8Overview
Is C18.8 (Malignant neoplasm of colon) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report malignant neoplasm of overlapping sites of colon on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does C18.8 group to?
When malignant neoplasm of overlapping sites of colon is the principal diagnosis on an inpatient stay, it groups to MS-DRG 374, 375, 376, with relative weights from 0.9243 to 2.1387 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of C18.8?
Under the General Equivalence Mappings, malignant neoplasm of overlapping sites of colon converts to ICD-9-CM 153.8 (malignant neo colon NEC). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:
- The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
- The condition places limitations on self-care, independent living, and social interactions.
