C13.1
BillableMalignant neoplasm of aryepiglottic fold, hypopharyngeal aspect
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is C13.1 an HCC code?
Yes. C13.1 maps to Breast, Prostate, Colorectal and Other Cancers and Tumors under the CMS-HCC V28 risk adjustment model (and Colorectal, Bladder, and Other 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 C13.1
For C13.1 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 C13.1 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
C13.1 is the ICD-10-CM diagnosis code for malignant neoplasm of aryepiglottic fold, hypopharyngeal aspect. Cancer of the aryepiglottic fold on the hypopharyngeal side, a tissue fold in the lower throat near the voice box. C13.1 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering malignant neoplasms of lip, oral cavity and pharynx (c00-c14).
Under the CMS-HCC V28 risk adjustment model, C13.1 maps to Breast, Prostate, Colorectal and Other Cancers and Tumors (HCC 21) with a community, non-dual, aged base RAF weight of 0.545. Under the older CMS-HCC V24 model, C13.1 maps to Colorectal, Bladder, and Other Cancers (HCC 11) with a community, non-dual, aged base RAF weight of 0.306. 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.
The aryepiglottic fold has both laryngeal and hypopharyngeal aspects; ensure the hypopharyngeal aspect is documented. Because C13.1 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 C13.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •The aryepiglottic fold has both laryngeal and hypopharyngeal aspects; ensure the hypopharyngeal aspect is documented
- •This location may affect swallowing and voice function
Clinical Significance
Malignant neoplasm of the aryepiglottic fold, hypopharyngeal aspect, is a cancer at the boundary between the larynx and hypopharynx. The critical coding distinction is that this code captures the hypopharyngeal (outer) surface of the aryepiglottic fold, while the laryngeal (inner) surface is coded as supraglottic laryngeal cancer.
Documentation Requirements
- ✓Pathology-confirmed malignancy
- ✓Documentation specifically stating hypopharyngeal aspect of aryepiglottic fold
- ✓Clear distinction between hypopharyngeal vs laryngeal surface involvement
- ✓Assessment of vocal cord mobility and laryngeal invasion
- ✓TNM staging using hypopharyngeal staging criteria
Excludes 2 — Not included here, may code separately
- malignant neoplasm of aryepiglottic fold or interarytenoid fold, laryngeal aspect (C32.1)