2027 ICD-10-CM Diagnosis Code C55Malignant neoplasm of uterus, part unspecified
ICD-10-CM Codes›C00–D49›C51-C58›C55
- Billable — Valid for Submission
- Risk Adjusts — HCC 23
- Chronic Condition
C55 is a billable ICD-10-CM diagnosis code for malignant neoplasm of uterus, part unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 731 through 733, 754 through 756. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Female reproductive system cancers - uterus.
For Medicare Advantage risk adjustment, C55 maps to CMS-HCC Category 23 (Prostate, Breast, and Other Cancers and Tumors) under the V28 model, adding a risk factor of about 0.186 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
C55 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Adenocarcinoma of uterus
- Adenosarcoma of uterus
- Carcinoma of uterus
- Carcinosarcoma of uterus
- Leiomyosarcoma of uterus
- Malignant neoplasm involving left fallopian tube by direct extension from uterus
- Malignant neoplasm involving right fallopian tube by direct extension from uterus
- Malignant neoplasm involving urinary bladder by direct extension from uterus
- Malignant neoplasm of uterus
- Malignant tumor involving an organ by direct extension from uterus
- Malignant tumor involving left ovary by direct extension from uterus
- Malignant tumor involving rectum by direct extension from uterus
- Malignant tumor involving right ovary by direct extension from uterus
- Malignant tumor involving vagina by direct extension from uterus
- Malignant tumor involving vulva by direct extension from uterus
- Primary adenosarcoma of uterus
- Primary carcinosarcoma of uterus
- Primary malignant neoplasm of uterus
- Primary myosarcoma of uterus
- Sarcoma of uterus
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to C55: its own notes plus those printed at block C51-C58 and Chapter 2. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- malignant neoplasm of skin of female genital organs
Notes
General instructions on how these codes are used.
- 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 C55, its category, or a range that includes it.
Applicable To 2
These notes mention C55.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Malignant Uterine Neoplasm
primary or metastatic malignant neoplasm involving the uterine corpus and/or the cervix.
Table of NeoplasmsClinical
Patient EducationClinical
Uterine Cancer
Uterine cancer is a cancer that forms in tissues of the uterus, which is sometimes called the womb. The uterus is the place where a fetus grows during pregnancy.
The full article covers:
- What is uterine cancer?
- Who is more likely to develop uterine cancer?
- What are the symptoms of uterine cancer?
- How is uterine cancer diagnosed?
- What are the treatments for uterine cancer?
- Can uterine cancer be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert C55 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About C55Overview
What is the ICD-10 code for malignant neoplasm of uterus, part unspecified?
The ICD-10-CM code for malignant neoplasm of uterus, part unspecified is C55. It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is C55 (Malignant neoplasm of uterus, part unspecified) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report malignant neoplasm of uterus, part unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does C55 group to?
When malignant neoplasm of uterus, part unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 732, 755, 756, 754, 733, 731, with relative weights from 0.8583 to 3.5462 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of C55?
Under the General Equivalence Mappings, malignant neoplasm of uterus, part unspecified converts to ICD-9-CM 179 (malig neopl uterus NOS). The mapping is a direct match.
What HCC is C55?
C55 (malignant neoplasm of uterus, part unspecified) maps to CMS-HCC Category 23 (Prostate, Breast, and Other Cancers and Tumors), commonly written as HCC 23, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 12 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. It does not map to any RxHCC in the Part D prescription drug model.
Does C55 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, C55 adds a risk adjustment factor of about 0.186 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.186 to 0.237 depending on the payment segment). A more severe related category (HCC 17, HCC 18, HCC 19, HCC 20, HCC 21, and HCC 22) supersedes it when both are reported. See the full factor table on the HCC 23 category page.
