C18.9 Malignant neoplasm of colon, unspecified

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Applicable to

• Malignant neoplasm of large intestine NOS

Applies from C18 Malignant neoplasm of colon

Excludes1 (never code together)

• malignant carcinoid tumors of the colon (C7A.02-)

Risk adjustment (HCC)

• CMS-HCC V28: HCC 22 — Bladder, Colorectal, and Other Cancers
• CMS-HCC V22: HCC 11 — Colorectal, Bladder, and Other Cancers
• ESRD V24: HCC 11

MS-DRG index

Defines the logic of DRG(s) 374-376 in MDC 06.

Approximate ICD-9-CM (GEMs)

• 153.9 Malignant neoplasm of colon, unspecified site

Code annotations containing back-references to C18.9

Back-references to C18

• Code Also: D13.91 Familial adenomatous polyposis ("malignant neoplasm of colon (C18.-)")

Diagnosis Index entries for C18.9

• Adenocarcinoma › in › adenomatous › polyposis coli
• Carcinoma (malignant) › in › adenomatous › polyposis coli
• Polyposis › coli › adenocarcinoma in
• Polyposis › coli › carcinoma in

Nearby codes

• 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 (this code)