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C33 ICD-10-CM Code: Malignant neoplasm of trachea

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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 guidance

Malignant neoplasm of trachea

Cancer of the trachea, which is the windpipe that carries air from the larynx to the lungs.

Buddy the Bee presenting code insight

Buddy Insight

Primary tracheal cancer is rare, accounting for less than 0.

CMS-HCC V28

HCC 20

RAF 1.136

CMS-HCC V24

HCC 9

RAF 1.024

ACA/HHS

HCC 9

Varies by metal level

ESRD/PACE

HCC 9

RAF 0.181

RXHCC

HCC 20

RAF 0.491

Code Book Path

Official
C3Malignant neoplasms of respiratory and intrathoracic organs (C30-C39)
C33Malignant neoplasm of trachea

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for C33 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for C33 in this effective period.

Related Child Codes

Official

ICD-10-CM does not list child codes under C33 for this display context.

Includes

Official

ICD-10-CM does not list Includes notes for C33 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for C33 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for C33 in this effective period.

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)

Code Also

Official

ICD-10-CM does not list Code Also instructions for C33 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance
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

MEAT Support

HCC Buddy guidance
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

Audit Caution

HCC Buddy guidance
Coding laryngeal or bronchial cancer with tracheal extension as primary tracheal cancer
Not confirming the tumor is primary to the trachea versus secondary involvement
Confusing tracheal cancer with extrinsic tracheal compression from mediastinal or thyroid masses
Failing to capture this rare diagnosis which carries a very high RAF weight

Common Mistakes

HCC Buddy guidance
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

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is C33 an HCC code?

Yes. C33 maps to Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model (and Lung and Other Severe Cancers under V24).

HCC Category Mapping

V28HCC 20, Lung and Other Severe Cancers
1.136
V24HCC 9, Lung and Other Severe Cancers
1.024
ESRDHCC 9, Lung and Other Severe Cancers
0.181
RxHCCHCC 20, Cancer, Liver and Intrahepatic Bile Duct
0.491

Each model's RAF is its CMS base weight for that model's standard population, so 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 segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.

Work C33 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for C33

For C33to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically, it has to be re-documented and supported each calendar year.

  • 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

Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed C33 during that encounter, not just copy-forwarded from a problem list.

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 community, non-dual, aged base RAF weight of 1.136. Under the older V24 model, C33 mapped to the same category but with a base RAF weight of 1.024, V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.

Tracheal cancers are relatively rare and often present at advanced stages. Because C33 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. 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, RAF weights, 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. These tumors carry a significant RAF weight because they are classified with severe cancers, require complex surgical management (tracheal resection), and have limited treatment options for advanced disease.

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

  • 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)

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

Code Hierarchy

└C33Malignant neoplasm of trachea
└C33Malignant neoplasm of trachea

Because C33 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

C33 maps to CMS-HCC V28 category 20, Lung and Other Severe Cancers. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works.

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