C33
BillableMalignant neoplasm of trachea
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
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
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. 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.
MEAT Criteria for C33
For C33 to 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.
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 0.000. Under the older V24 model, C33 mapped to the same category but with a base RAF weight of 0.973 — 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