1. Home
  2. ICD-10-CM Codes List
  3. C00–D49
  4. C15-C26
  5. Malignant neoplasm of colon (C18)

Malignant neoplasm of colon (C18)

ICD-10 code C18 and its subcodes specifically identify different types of malignant neoplasms (cancers) of the colon. These codes are used to classify and document the precise location of colon cancer, whether it affects the cecum, appendix, ascending colon, or other parts of the colon.

The ICD-10 code for malignant neoplasm of colon helps healthcare providers distinguish cancer sites within the large intestine, which is critical for treatment planning and reporting. For instance, code C18.0 covers cancers such as "adenocarcinoma of cecum" or "primary carcinoma of cecum," while C18.1 includes malignancies of the appendix, including "primary mucinous adenocarcinoma." Similarly, other codes like C18.2 and C18.3 describe malignant tumors at the ascending colon and hepatic flexure, respectively. The term "malignant tumor of the sigmoid colon" corresponds to C18.7. If the cancer's exact location isn't specified, C18.9 represents an unspecified malignant neoplasm of the colon. These synonyms alongside their respective codes assist medical coders and healthcare professionals in selecting the most accurate code for colorectal malignancies.

Instructional Notations

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

Clinical Terms

The following clinical terms provide additional context, helping users better understand the clinical background and common associations for each diagnosis listed in this section. Including related terms alongside ICD-10-CM codes supports coders, billers, and healthcare professionals in improving accuracy, enhancing documentation, and facilitating research or patient education.

Appendiceal Neoplasms

Tumors or cancer of the APPENDIX.

Appendix

A worm-like blind tube extension from the CECUM.

Colon

The segment of LARGE INTESTINE between the CECUM and the RECTUM. It includes the ASCENDING COLON; the TRANSVERSE COLON; the DESCENDING COLON; and the SIGMOID COLON.