What is ICD-10 code C11.3?

C11.3 is the ICD-10-CM diagnosis code for Malignant neoplasm of anterior wall of nasopharynx. Cancer that forms in the front wall of the nasopharynx, the uppermost part of the throat. It belongs to the ICD-10-CM chapter for neoplasms (c00-d49). C11.3 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. C11.3 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. C11.3 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. C11.3 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Which HCC does C11.3 map to under V28?

C11.3 maps to CMS-HCC V28 HCC 21 (Lymphoma and Other Cancers). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

2026 ICD-10-CM C11.3: Malignant neoplasm

C11.3 maps to CMS-HCC V28 21. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · HCC coding software

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Code lookupC11.3

Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of lip, oral cavity and pharynx (C00-C14)

C11.3

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Malignant neoplasm of anterior wall of nasopharynx

Cancer that forms in the front wall of the nasopharynx, the uppermost part of the throat.

Buddy Insight

Malignant neoplasm of the anterior wall of the nasopharynx involves the surface facing the nasal cavity, including the choana (posterior nasal apertures).

Overview Risk Models Code Book Documentation Audit Notes Edition comparison

CMS-HCC V28

Mapped

HCC 21

Lymphoma and Other Cancers

Code-level coefficient reference

CMS-HCC V24

Historical

Not used for standard CY2026 Medicare Advantage payment. Select a historical period to review V24.

Not used for CY2026 payment

ACA/HHS

Mapped

HCC 011

HHS-HCC 011 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 11

Colorectal/Bladder/and Other ...

Code-level coefficient reference

RXHCC

N/A

—

Not risk-adjusted for this model/period.

Not mapped

Code Book Path

Official

C11Malignant neoplasm of nasopharynx C11.3Malignant neoplasm of anterior wall of nasopharynx

Inclusion Terms

Official

Malignant neoplasm of floor of nasopharynx
Malignant neoplasm of nasopharyngeal (anterior) (posterior) surface of soft palate
Malignant neoplasm of posterior margin of nasal choana
Malignant neoplasm of posterior margin of nasal septum

Excludes 2

Official

No Excludes 2 notes are included in this display for C11.3. Check the code and parent instructions in the Code Book.

Related Codes

Official

C11.0Malignant neoplasm of superior wall of nasopharynx C11.1Malignant neoplasm of posterior wall of nasopharynx C11.2Malignant neoplasm of lateral wall of nasopharynx C11.8Malignant neoplasm of overlapping sites of nasopharynx C11.9Malignant neoplasm of nasopharynx, unspecified

Includes

Official

No Includes notes are included in this display for C11.3. Check the code and parent instructions in the Code Book.

Excludes 1

Official

No Excludes 1 notes are included in this display for C11.3. Check the code and parent instructions in the Code Book.

Code First

Official

No Code First sequencing instructions are included in this display for C11.3. Check the code and parent instructions in the Code Book.

Use Additional

Official

code to identify:Inherited from C11
exposure to environmental tobacco smoke (Z77.22)Inherited from C11
exposure to tobacco smoke in the perinatal period (P96.81)Inherited from C11
history of tobacco dependence (Z87.891)Inherited from C11
occupational exposure to environmental tobacco smoke (Z57.31)Inherited from C11
tobacco dependence (F17.-)Inherited from C11
tobacco use (Z72.0)Inherited from C11

Code Also

Official

No Code Also instructions are included in this display for C11.3. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance

Pathology-confirmed malignancy with histological type

Documentation specifying anterior wall of nasopharynx

EBV status

Assessment of nasal cavity extension through choana

MEAT Support

HCC Buddy guidance

Pathology-confirmed malignancy with histological type

Documentation specifying anterior wall of nasopharynx

EBV status

Assessment of nasal cavity extension through choana

Audit Caution

HCC Buddy guidance

Confusing primary nasal cavity cancer (C30.0) with nasopharyngeal cancer extending into the nose — the primary site determines the code

Not documenting whether nasal symptoms are due to anterior wall nasopharyngeal cancer or a separate nasal cavity process

Using the unspecified nasopharynx code when endoscopy or imaging clearly shows anterior wall involvement

Failing to assess choanal involvement which may affect surgical approach

Common Mistakes

HCC Buddy guidance

C30.0 — Malignant neoplasm of nasal cavity; anterior wall nasopharyngeal tumors may extend into the nasal cavity

C11.1 — Posterior wall of nasopharynx; the anterior wall faces the nose, the posterior wall faces the back

C11.8 — Overlapping sites; use when tumor involves both anterior wall and other nasopharyngeal surfaces

C11.9 — Nasopharynx, unspecified; avoid when anterior wall is documented

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 C11.3 an HCC code?

Yes. C11.3 (Malignant neoplasm of anterior wall of nasopharynx) maps to HCC 21, Lymphoma and Other Cancers under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.671. 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: C11.3 is billable and maps to V28 HCC 21, Lymphoma and Other Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: C11.3
Description: Malignant neoplasm of anterior wall of nasopharynx
HCC (V28): HCC 21 — Lymphoma and Other Cancers
RAF reference coefficient: 0.671
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 21, Lymphoma and Other Cancers

0.671

ESRDHCC 11, Colorectal/Bladder/and Other Cancers

Not separately weighted

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 C11.3 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for C11.3

For C11.3, 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

C11.3 is the ICD-10-CM diagnosis code for malignant neoplasm of anterior wall of nasopharynx. Cancer that forms in the front wall of the nasopharynx, the uppermost part of the throat. C11.3 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, C11.3 maps to Lymphoma and Other Cancers (HCC 21) with a source-labeled community, non-dual, aged reference coefficient of 0.671. No V24 mapping is shown for C11.3; use the applicable model and payment year when reviewing the V28 mapping. 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.

Ensure the anterior wall location is explicitly documented in the pathology or imaging report. For C11.3, 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 C11.3 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Ensure the anterior wall location is explicitly documented in the pathology or imaging report
•This location may be associated with different symptom presentations compared to posterior wall tumors

Clinical Significance

Malignant neoplasm of the anterior wall of the nasopharynx involves the surface facing the nasal cavity, including the choana (posterior nasal apertures). This location may cause nasal obstruction and epistaxis as early symptoms, and tumors may extend anteriorly into the nasal cavity, complicating primary site determination.

Documentation Requirements

✓Pathology-confirmed malignancy with histological type
✓Documentation specifying anterior wall of nasopharynx
✓EBV status
✓Assessment of nasal cavity extension through choana
✓MRI staging including evaluation of both nasal and nasopharyngeal extent

Commonly Confused Codes

•C30.0: Malignant neoplasm of nasal cavity; anterior wall nasopharyngeal tumors may extend into the nasal cavity
•C11.1: Posterior wall of nasopharynx; the anterior wall faces the nose, the posterior wall faces the back
•C11.8: Overlapping sites; use when tumor involves both anterior wall and other nasopharyngeal surfaces
•C11.9: Nasopharynx, unspecified; avoid when anterior wall is documented