2027 ICD-10-CM Diagnosis Code C66Malignant neoplasm of ureter

ICD-10-CM Codes›C00–D49›C64-C68›C66

ICD-10-CM C66
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

C66 is a non-billable ICD-10-CM category code for malignant neoplasm of ureter, so it cannot be submitted on claims. Use a more specific code from this category instead, such as C66.1, C66.2, and C66.9.

Code Identity

ICD-10-CM Code
C66
Billable Status
No — Non-Billable Category
Code Describes
Malignant neoplasm of ureter
Short Description
Malignant neoplasm of ureter
Same as the full description in the CMS dataset.
Chapter
C64-C68
Malignant neoplasms of urinary tract

Code Classification

ChapterC00–D49Neoplasms
SectionC64-C68Malignant neoplasms of urinary tract
CategoryC66Malignant neoplasm of ureter
This CodeC66Malignant neoplasm of ureter

Specific Coding for Malignant neoplasm of ureterOverview

Non-specific codes like C66 require more characters. Use one of these billable codes instead:

  • Use C66.1 for Malignant neoplasm of right ureter

  • Use C66.2 for Malignant neoplasm of left ureter

  • Use C66.9 for Malignant neoplasm of unspecified ureter

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to C66: its own notes plus those printed at Chapter 2. A note printed at a category, block or chapter applies to every code under it.

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

  • malignant neoplasm of ureteric orifice of bladder (C67.6)

Notes

General instructions on how these codes are used.

From Chapter 2 (C00-D49) Neoplasms applies to 1,730 codes
  • Functional activity
  • All neoplasms are classified in this chapter, whether they are functionally active or not. An additional code from Chapter 4 may be used, to identify functional activity associated with any neoplasm.
  • Morphology [Histology]
  • Chapter 2 classifies neoplasms primarily by site (topography), with broad groupings for behavior, malignant, in situ, benign, etc. The Table of Neoplasms should be used to identify the correct topography code. In a few cases, such as for malignant melanoma and certain neuroendocrine tumors, the morphology (histologic type) is included in the category and codes.
  • Primary malignant neoplasms overlapping site boundaries
  • A primary malignant neoplasm that overlaps two or more contiguous (next to each other) sites should be classified to the subcategory/code .8 ('overlapping lesion'), unless the combination is specifically indexed elsewhere. For multiple neoplasms of the same site that are not contiguous, such as tumors in different quadrants of the same breast, codes for each site should be assigned.
  • Malignant neoplasm of ectopic tissue
  • Malignant neoplasms of ectopic tissue are to be coded to the site mentioned, e.g., ectopic pancreatic malignant neoplasms are coded to pancreas, unspecified (C25.9).

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name C66, its category, or a range that includes it.

Applicable To 2

These notes mention C66.

  • Z80.5 Family history of malignant neoplasm of urinary tract
    Conditions classifiable to C64-C68 names C64-C68, which includes this code
  • Z85.5 Personal history of malignant neoplasm of urinary tract
    Conditions classifiable to C64-C68 names C64-C68, which includes this code

Clinical InformationClinical

  • Malignant Ureter Neoplasm

    a primary or metastatic malignant tumor involving the ureter. the majority are carcinomas.

Patient EducationClinical

Cancer

Cancer is not just one disease but many diseases. Cancer begins in your cells, which are the building blocks of your body. Usually, your body forms new cells as needed, replacing old cells that die. Sometimes this process goes wrong. New cells grow even when you don't need them, and old cells don't die when they should.

The full article covers:

  • What is cancer?
  • What are the types of cancer?
  • How does cancer develop?
  • What are the symptoms of cancer?
  • How is cancer diagnosed?
  • What are the treatments for cancer?
  • Can cancer be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About C66Overview

What is the ICD-10 code for malignant neoplasm of ureter?

C66 is the ICD-10-CM category for malignant neoplasm of ureter, but it is a non-billable header: claims need a more specific code from this category, listed on this page.

Is C66 (Malignant neoplasm of ureter) a billable code?

No. This is a category header that groups the codes for malignant neoplasm of ureter, and headers cannot be submitted on claims. Claims for malignant neoplasm of ureter need a more specific code from this category, such as C66.1, C66.2, and C66.9.

Can C66 be reported with C67.6?

Not as a rule. The Excludes1 note on C66 lists "malignant neoplasm of ureteric orifice of bladder (C67.6)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).