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C11.0 ICD-10-CM Code: Malignant neoplasm of superior wall of nasopharynx

C11.0 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 lookupC11.0

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

C11.0

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

Malignant neoplasm of superior wall of nasopharynx

Cancer located in the upper wall of the nasopharynx, the uppermost part of the throat behind the nose.

Buddy the Bee presenting code insight

Buddy Insight

Malignant neoplasm of the superior wall of the nasopharynx involves cancer of the roof of the upper throat behind the nose, near the base of the skull.

OverviewRisk ModelsCode BookDocumentationAuditNotesEdition comparison

CMS-HCC V28

HCC 21

Coefficient HCC 21: 0.671 (Community Non-Dual Aged (CNA))

CMS-HCC V24

Historical

Historical

Not used for CY2026 payment

ACA/HHS

HCC 011

Code-level coefficient reference

ESRD/PACE

HCC 11

Code-level coefficient reference

RXHCC

N/A

—

Not mapped

Code Book Path

Official
C11Malignant neoplasm of nasopharynxC11.0Malignant neoplasm of superior wall of nasopharynx

Inclusion Terms

Official
  • Malignant neoplasm of roof of nasopharynx

Excludes 2

Official

No Excludes 2 notes are included in this display for C11.0. Check the code and parent instructions in the Code Book.

Related Codes

Official
C11.1Malignant neoplasm of posterior wall of nasopharynxC11.2Malignant neoplasm of lateral wall of nasopharynxC11.3Malignant neoplasm of anterior wall of nasopharynxC11.8Malignant neoplasm of overlapping sites of nasopharynxC11.9Malignant neoplasm of nasopharynx, unspecified

Includes

Official

No Includes notes are included in this display for C11.0. Check the code and parent instructions in the Code Book.

Excludes 1

Official

No Excludes 1 notes are included in this display for C11.0. Check the code and parent instructions in the Code Book.

Code First

Official

No Code First sequencing instructions are included in this display for C11.0. 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 C11.0. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance
Pathology-confirmed malignancy with histological type (nonkeratinizing carcinoma common in EBV-associated cases)
Specific documentation of superior wall or roof of nasopharynx as primary site
EBV serology and tumor EBV-encoded RNA (EBER) status
MRI assessment of skull base invasion

MEAT Support

HCC Buddy guidance
Pathology-confirmed malignancy with histological type (nonkeratinizing carcinoma common in EBV-associated cases)
Specific documentation of superior wall or roof of nasopharynx as primary site
EBV serology and tumor EBV-encoded RNA (EBER) status
MRI assessment of skull base invasion

Audit Caution

HCC Buddy guidance
Confusing superior wall (roof) with posterior wall (back) of the nasopharynx — these are distinct anatomical sites
Not documenting EBV status which is pathognomonic for certain nasopharyngeal carcinoma subtypes
Missing skull base invasion assessment which is critical for tumors at the nasopharyngeal roof
Using nasal cavity codes (C30.x) when the primary site is the nasopharynx with nasal extension

Common Mistakes

HCC Buddy guidance
C11.1 — Posterior wall of nasopharynx; the superior wall (roof) is distinct from the posterior (back) wall
C11.2 — Lateral wall of nasopharynx; distinguish roof from side walls
C11.8 — Overlapping sites of nasopharynx; use when tumor spans multiple nasopharyngeal walls
C30.0 — Nasal cavity; nasopharyngeal tumors may extend anteriorly into the nasal cavity

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 C11.0 an HCC code?

Yes. C11.0 (Malignant neoplasm of superior 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: C11.0 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
C11.0
Description
Malignant neoplasm of superior 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 C11.0 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for C11.0

For C11.0, 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

C11.0 is the ICD-10-CM diagnosis code for malignant neoplasm of superior wall of nasopharynx. Cancer located in the upper wall of the nasopharynx, the uppermost part of the throat behind the nose. C11.0 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, C11.0 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 C11.0; 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.

The superior wall of the nasopharynx is the roof or top surface of the nasopharynx, near the base of the skull. For C11.0, 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 C11.0 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •The superior wall of the nasopharynx is the roof or top surface of the nasopharynx, near the base of the skull
  • •Distinguish from other nasopharyngeal sites such as lateral wall (C11.2), posterior wall (C11.3), or anterior wall (C11.3)

Clinical Significance

Malignant neoplasm of the superior wall of the nasopharynx involves cancer of the roof of the upper throat behind the nose, near the base of the skull. This is clinically significant because proximity to the skull base means early intracranial extension risk, and nasopharyngeal cancers are strongly associated with Epstein-Barr virus in endemic populations.

Documentation Requirements

  • ✓Pathology-confirmed malignancy with histological type (nonkeratinizing carcinoma common in EBV-associated cases)
  • ✓Specific documentation of superior wall or roof of nasopharynx as primary site
  • ✓EBV serology and tumor EBV-encoded RNA (EBER) status
  • ✓MRI assessment of skull base invasion
  • ✓TNM staging per nasopharyngeal cancer-specific staging criteria

Commonly Confused Codes

  • •C11.1: Posterior wall of nasopharynx; the superior wall (roof) is distinct from the posterior (back) wall
  • •C11.2: Lateral wall of nasopharynx; distinguish roof from side walls
  • •C11.8: Overlapping sites of nasopharynx; use when tumor spans multiple nasopharyngeal walls
  • •C30.0: Nasal cavity; nasopharyngeal tumors may extend anteriorly into the nasal cavity

Child Codes

C11.0Malignant neoplasm of superior wall of nasopharynx
HCC 21
C11.1Malignant neoplasm of posterior wall of nasopharynx
HCC 21
C11.2Malignant neoplasm of lateral wall of nasopharynx
HCC 21
C11.3Malignant neoplasm of anterior wall of nasopharynx
HCC 21
C11.8Malignant neoplasm of overlapping sites of nasopharynx
HCC 21
C11.9Malignant neoplasm of nasopharynx, unspecified
HCC 21

Code Hierarchy

└C11Malignant neoplasm of nasopharynx└C11.0Malignant neoplasm of superior wall of nasopharynx
└C11.0Malignant neoplasm of superior wall of nasopharynx

Also searched as

  • C11 0
  • C110

For C11.0, 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.

C11.0 maps to CMS-HCC V28 category 21, Lymphoma and Other Cancers. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. The mapping identifies a payment HCC category for C11.0. Review its source-labeled HCC coefficient above, check the RAF Calculator with complete member context for CMS-HCC V28 PY2026, and confirm the documentation the chart needs before the code is submitted. HCC Buddy shows no RAF score unless every required source and calculation check passes.

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