Malignant neoplasm of ureter (C66) ICD-10-CM
The C66 code range covers malignant neoplasm of ureter with 4 ICD-10-CM diagnosis codes. 3 of them are billable and valid for claim submission in fiscal year 2026, 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 neoplasm of ureteric orifice of bladder C67.6
Codes in the C66 Range 4 codes · 3 billable
About the C66 Code Range
The ICD-10 code C66 and its subcodes identify malignant tumors located in the ureter, the tube that carries urine from the kidneys to the bladder. These codes specify whether the cancer affects the right ureter (C66.1), left ureter (C66.2), or an unspecified ureter (C66.9).
These codes are used to classify cancers such as transitional cell carcinoma—also known as primary transitional cell carcinoma of the ureter or upper urinary tract—that originate in the lining of the ureter. The detailed subcodes help healthcare providers and medical coders indicate the exact location of the malignancy for accurate diagnosis, treatment planning, and billing. For example, C66.1 is assigned for malignant neoplasm of the right ureter, while C66.2 applies to the left ureter. When the specific ureter is not documented, C66.9 is appropriate. This section of ICD-10 applies specifically to urinary system cancers involving the ureter and helps distinguish these from other genitourinary malignancies. Using the correct code ensures proper clinical communication and data tracking for ureter cancers.
Questions About This Page
How many billable codes are in the C66 range?
Of the 4 codes in this range, 3 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the C66 range classify?
The range classifies malignant neoplasm of ureter. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
