C33 ICD-10-CM Code: Malignant neoplasm of trachea
C33 maps to CMS-HCC V28 20. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · free HCC coding tools
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FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of respiratory and intrathoracic organs (C30-C39)
C33
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceMalignant neoplasm of trachea
Cancer of the trachea, which is the windpipe that carries air from the larynx to the lungs.
Buddy Insight
Primary tracheal cancer is rare, accounting for less than 0.
CMS-HCC V28
MappedHCC 20
Coefficient HCC 20: 1.136 (Community Non-Dual Aged (CNA))
CMS-HCC V24
HistoricalHistorical
Not used for CY2026 payment
ACA/HHS
MappedHCC 009
Code-level coefficient reference
ESRD/PACE
MappedHCC 9
Code-level coefficient reference
RXHCC
MappedHCC 20
Code-level coefficient reference
Code Book Path
Inclusion Terms
OfficialNo inclusion terms are included in this display for C33. Check the code and parent instructions in the Code Book.
Excludes 2
OfficialNo Excludes 2 notes are included in this display for C33. Check the code and parent instructions in the Code Book.
Related Codes
No related codes are included in this display for C33. Check the Code Book for the complete code path.
Includes
Official- malignant neoplasm of middle earInherited from C30-C39
Excludes 1
Official- mesothelioma (C45.-)Inherited from C30-C39
Code First
OfficialNo Code First sequencing instructions are included in this display for C33. Check the code and parent instructions in the Code Book.
Use Additional
Official- 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)
Code Also
OfficialNo Code Also instructions are included in this display for C33. Check the code and parent instructions in the Code Book.
Buddy Documentation Tip
MEAT Support
Audit Caution
Common Mistakes
Current with CMS: FY2026 ICD-10-CM Apr 1 update (effective Apr 1 – Sep 30, 2026) · CMS-HCC V28, 100% phased in for payment year 2026. FY2027 code set already staged for October 1, 2026. How HCC Buddy stays current →
Is C33 an HCC code?
Yes. C33 (Malignant neoplasm of trachea) maps to HCC 20, Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 1.136. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes. It is billable for payment year 2026.
Coder answer: C33 is billable and maps to V28 HCC 20, Lung and Other Severe Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.
- Code
- C33
- Description
- Malignant neoplasm of trachea
- HCC (V28)
- HCC 20 — Lung and Other Severe Cancers
- RAF reference coefficient
- 1.136
- Billable
- Yes
- Payment year
- 2026
HCC Category Mapping
These are source-labeled model coefficients, not member totals. A category may still be removed by hierarchy or model cleanup rules. Weights are not directly comparable across models: CMS-HCC V28 and V24 use Community, Non-Dual, Aged; ESRD uses the dialysis continuing-enrollee model; RxHCC is the Part D continuing-enrollee, non-low-income, aged weight (a larger scale than CMS-HCC). ACA/HHS has no single weight — it varies by metal level. Actual per-patient RAF contribution depends on member context, hierarchy and cleanup rules, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains available for historical review.
Work C33 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →
MEAT review for C33
For C33, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Coder workflow notes
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What This Code Means
C33 is the ICD-10-CM diagnosis code for malignant neoplasm of trachea. Cancer of the trachea, which is the windpipe that carries air from the larynx to the lungs. C33 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of respiratory and intrathoracic organs (c30-c39).
Under the CMS-HCC V28 risk adjustment model, C33 maps to Lung and Other Severe Cancers (HCC 20) with a source-labeled community, non-dual, aged reference coefficient of 1.136. For CY2026 non-PACE Medicare Advantage, CMS uses 100% of the 2024 CMS-HCC model (V28). PACE uses a separate model blend. Source-labeled code-level coefficients are references, not member totals. Actual contribution depends on complete member context, hierarchy and cleanup rules, interactions, and model year. HCC Buddy's RAF Calculator supports CMS-HCC V28 PY2026 and shows no score unless every required source and calculation check passes.
Tracheal cancers are relatively rare and often present at advanced stages. For C33, confirm that the documentation supports the diagnosis and meets the applicable coding, encounter, program and payer requirements. MEAT (Monitor, Evaluate, Assess, or Treat) is a review mnemonic, not a universal CMS coding rule. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, source-labeled coefficient references, and MEAT documentation criteria for C33 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Tracheal cancers are relatively rare and often present at advanced stages
- •Ensure the cancer is documented as originating in the trachea rather than being a secondary involvement from lung or laryngeal cancer
Clinical Significance
Primary tracheal cancer is rare, accounting for less than 0.1% of all malignancies. The most common types are squamous cell carcinoma and adenoid cystic carcinoma.
Documentation Requirements
- ✓Pathology confirmation with histological type (squamous cell, adenoid cystic, carcinoid)
- ✓Bronchoscopy and imaging documenting tumor location within the trachea
- ✓Assessment of airway obstruction percentage
- ✓Confirmation that the trachea is the primary site, not extension from laryngeal or bronchial cancers
- ✓TNM staging and treatment plan
Use Additional Code
Commonly Confused Codes
- •C32.2: Subglottic cancer: The boundary is at the inferior cricoid cartilage; tumors above this are subglottic
- •C34.00: Main bronchus cancer: The boundary is at the carina; tumors below this are bronchial
- •D14.2: Benign neoplasm of trachea: Tracheal papillomas and chondromas are benign; confirm malignancy
- •C78.39: Secondary malignant neoplasm of other respiratory organs: Metastatic disease to the trachea uses secondary codes