2026 ICD-10-CM Diagnosis Code C33Malignant neoplasm of trachea
ICD-10-CM Codes›C00–D49›C30-C39›C33
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 20
- Chronic Condition
C33 is a billable ICD-10-CM diagnosis code for malignant neoplasm of trachea. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 180 through 182. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 44 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Respiratory cancers.
For Medicare Advantage risk adjustment, C33 maps to CMS-HCC Category 20 (Lung and Other Severe Cancers) under the V28 model, adding a risk factor of about 1.136 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
C33 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 2026.
Source: CMS Payment Year 2026 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.
- Acinar cell carcinoma of trachea
- Adenocarcinoma of trachea
- Adenoid cystic carcinoma of trachea
- Adenosquamous carcinoma of trachea
- Basaloid squamous cell carcinoma of trachea
- Clear cell adenocarcinoma of trachea
- Clear cell squamous cell carcinoma of trachea
- Giant cell carcinoma of trachea
- Lymphoepithelial carcinoma of trachea
- Malignant neoplasm of carina of trachea
- Malignant neoplasm of cartilage of trachea
- Malignant neoplasm of mucosa of trachea
- Malignant neoplasm of trachea
- Mucinous adenocarcinoma of trachea
- Mucinous cystadenocarcinoma of trachea
- Myoepithelial carcinoma
- Myoepithelial carcinoma of trachea
- Neoplasm of carina
- Neoplasm of lower respiratory tract and mediastinum
- Papillary adenocarcinoma of trachea
- Papillary squamous cell carcinoma of trachea
- Primary acantholytic squamous cell carcinoma
- Primary acinar cell carcinoma of trachea
- Primary adenocarcinoma of trachea
- Primary adenoid cystic carcinoma of trachea
- Primary adenosquamous carcinoma of trachea
- Primary adenosquamous cell carcinoma
- Primary basaloid squamous cell carcinoma of trachea
- Primary clear cell adenocarcinoma of trachea
- Primary clear cell squamous cell carcinoma of trachea
- Primary giant cell carcinoma of trachea
- Primary lymphoepithelial carcinoma
- Primary lymphoepithelial carcinoma of trachea
- Primary malignant epithelial neoplasm of trachea
- Primary malignant neoplasm of carina
- Primary malignant neoplasm of trachea
- Primary mucinous adenocarcinoma of trachea
- Primary mucinous cystadenocarcinoma of trachea
- Primary mucoepidermoid carcinoma of trachea
- Primary myoepithelial carcinoma of trachea
- Primary papillary adenocarcinoma of trachea
- Primary papillary squamous cell carcinoma of trachea
- Primary salivary gland type carcinoma of trachea
- Primary signet ring cell carcinoma of trachea
- Primary solid carcinoma of trachea
- Primary spindle cell carcinoma of trachea
- Primary spindle cell squamous cell carcinoma
- Primary squamous cell adenoid carcinoma of trachea
- Primary squamous cell carcinoma of trachea
- Primary undifferentiated carcinoma of trachea
- Primary verrucous carcinoma of trachea
- Primary verrucous squamous cell carcinoma
- Signet ring cell carcinoma of trachea
- Solid carcinoma of trachea
- Spindle cell carcinoma of trachea
- Squamous cell adenoid carcinoma of trachea
- Squamous cell carcinoma of trachea
- Undifferentiated carcinoma of trachea
- Verrucous carcinoma of trachea
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Use Additional Code
- code to identify:
- exposure to environmental tobacco smoke Z77.22
- exposure to tobacco smoke in the perinatal period P96.81
- history of tobacco dependence Z87.891
- occupational exposure to environmental tobacco smoke Z57.31
- tobacco dependence F17
- tobacco use Z72.0
The “use additional code” indicates that a secondary code could be used to further specify the patient’s condition. This note is not mandatory and is only used if enough information is available to assign an additional code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Table of NeoplasmsClinical
Anatomical sites in the Table of Neoplasms that reference this code family.
Patient EducationClinical
Head and Neck Cancer
Head and neck cancer is the name for cancers that develop in the mouth, nose and sinuses, salivary glands, and throat and voice box (larynx). Most head and neck cancers are squamous cell cancers. They begin in the moist tissues that line the head and neck. The cancer cells may spread into deeper tissue as the cancer grows.
The full article covers:
- What is head and neck cancer?
- Who is more likely to develop head and neck cancer?
- What are the symptoms of head and neck cancer?
- How is head and neck cancer diagnosed?
- What are the treatments for head and neck cancer?
- Can head and neck cancer be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert C33 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About C33Overview
What is the ICD-10 code for malignant neoplasm of trachea?
The ICD-10-CM code for malignant neoplasm of trachea is C33. It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is C33 (Malignant neoplasm of trachea) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report malignant neoplasm of trachea on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does C33 group to?
When malignant neoplasm of trachea is the principal diagnosis on an inpatient stay, it groups to MS-DRG 180, 181, 182, with relative weights from 0.7440 to 1.7660 depending on complications. Higher weights mean higher Medicare reimbursement.
Is C33 a CC or MCC?
CMS lists C33 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 44 closely related codes in its exclusion list.
What is the ICD-9 equivalent of C33?
Under the General Equivalence Mappings, malignant neoplasm of trachea converts to ICD-9-CM 162.0 (malignant neo trachea). The mapping is a direct match.
What HCC is C33?
C33 (malignant neoplasm of trachea) maps to CMS-HCC Category 20 (Lung and Other Severe Cancers), commonly written as HCC 20, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 9 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 20.
Does C33 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, C33 adds a risk adjustment factor of about 1.136 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.672 to 1.214 depending on the payment segment). A more severe related category (HCC 17, HCC 18, and HCC 19) supersedes it when both are reported. See the full factor table on the HCC 20 category page.
