Malignant neoplasm of colon (C18) ICD-10-CM
The C18 code range covers malignant neoplasm of colon with 11 ICD-10-CM diagnosis codes. 10 of them are billable and valid for claim submission in fiscal year 2027, and the category headers group them but cannot themselves be billed.
Type 1 Excludes
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
- malignant carcinoid tumors of the colon C7A.02
Codes in the C18 Range 11 codes · 10 billable
- C18 Malignant neoplasm of colonNon-billable
- C18.0 Malignant neoplasm of cecum
- C18.1 Malignant neoplasm of appendix
- C18.2 Malignant neoplasm of ascending colon
- C18.3 Malignant neoplasm of hepatic flexure
- C18.4 Malignant neoplasm of transverse colon
- C18.5 Malignant neoplasm of splenic flexure
- C18.6 Malignant neoplasm of descending colon
- C18.7 Malignant neoplasm of sigmoid colon
- C18.8 Malignant neoplasm of overlapping sites of colon
- C18.9 Malignant neoplasm of colon, unspecified
Clinical Terms in This Code Range
Definitions from the National Library of Medicine for conditions coded in the C18 range.
Malignant Appendix Neoplasm
A primary or metastatic malignant neoplasm that affects the appendix.
Malignant Cecum Neoplasm
A primary or metastatic malignant neoplasm that affects the cecum. Representative examples include carcinoma, lymphoma, and sarcoma.
Malignant Colon Neoplasm
A primary or metastatic malignant neoplasm that affects the colon. Representative examples include carcinoma, lymphoma, and sarcoma.
Malignant Hepatic Flexure Neoplasm
A primary or metastatic malignant neoplasm that affects the hepatic flexure.
Malignant Sigmoid Colon Neoplasm
A primary or metastatic malignant neoplasm that affects the sigmoid colon.
About the C18 Code Range
A malignant neoplasm of the colon is cancer that begins in the colon or spreads there from elsewhere.
C18 is divided by named site: the cecum (C18.0), appendix (C18.1), ascending colon (C18.2), transverse colon (C18.4), descending colon (C18.6), and sigmoid colon (C18.7). Separate subdivisions identify the hepatic and splenic flexures, which are bends in the colon: C18.3 and C18.5.
C18.8 describes overlapping sites of the colon, while C18.9 leaves the colon site unspecified.
Questions About This Page
How many billable codes are in the C18 range?
Of the 11 codes in this range, 10 are billable and valid for claim submission from October 1, 2026 through September 30, 2027. Category header codes group them but cannot be reported on claims.
What does the C18 range classify?
The range classifies malignant neoplasm of colon. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2027 ICD-10-CM Tabular List and order file, effective October 1, 2026 through September 30, 2027.
