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C34.81 ICD-10-CM Code: Malignant neoplasm of overlapping sites of right bronchus and lung

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FY 2026 Apr update / Neoplasms (C00-D49) / Malignant neoplasms of respiratory and intrathoracic organs (C30-C39)

C34.81

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

Malignant neoplasm of overlapping sites of right bronchus and lung

Cancer that involves multiple areas of the right lung and/or right bronchus.

Buddy the Bee presenting code insight

Buddy Insight

Right-sided overlapping lung cancer indicates locally advanced disease crossing anatomical boundaries within the right lung.

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
C34Malignant neoplasm of bronchus and lung
C34.8Malignant neoplasm of overlapping sites of bronchus and lung
C34.81Malignant neoplasm of overlapping sites of right bronchus and lung

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for C34.81 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for C34.81 in this effective period.

Related Child Codes

Official
C34.80Malignant neoplasm of overlapping sites of unspecified bronchus and lung
C34.82Malignant neoplasm of overlapping sites of left bronchus and lung

Includes

Official

ICD-10-CM does not list Includes notes for C34.81 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for C34.81 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for C34.81 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for C34.81 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for C34.81 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance
Imaging showing tumor involvement of multiple right lung regions
Pathology confirming single primary neoplasm crossing anatomical boundaries
Documentation of which specific right-sided sites are involved
TNM staging and surgical resection planning

MEAT Support

HCC Buddy guidance
Imaging showing tumor involvement of multiple right lung regions
Pathology confirming single primary neoplasm crossing anatomical boundaries
Documentation of which specific right-sided sites are involved
TNM staging and surgical resection planning

Audit Caution

HCC Buddy guidance
Coding overlapping sites when a single lobe is clearly the primary site with minor fissural extension
Not documenting which specific lobes or regions are involved
Confusing bilobar primary disease with satellite nodules (which may represent separate staging)
Using less specific codes when overlapping right-sided involvement is documented

Common Mistakes

HCC Buddy guidance
C34.82 — Overlapping left lung: Verify right laterality
C34.80 — Overlapping, unspecified side: Use C34.81 when right side is documented
C34.11/C34.2/C34.31 — Single lobe codes: Use when the primary site is identifiable despite extension
C34.91 — Right lung, unspecified part: C34.81 is more specific with overlapping site information

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 C34.81 an HCC code?

Yes. C34.81 (Malignant neoplasm of overlapping sites of right bronchus and lung) maps to Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model (and Lung and Other Severe Cancers under V24), with a community non-dual aged RAF of 1.136. It is billable for payment year 2026.

Coder answer: C34.81 is billable and maps to V28 HCC 20, Lung and Other Severe Cancers. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code
C34.81
Description
Malignant neoplasm of overlapping sites of right bronchus and lung
HCC (V28)
HCC 20 — Lung and Other Severe Cancers
RAF
1.136
Billable
Yes
Payment year
2026

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 C34.81 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for C34.81

For C34.81 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 C34.81 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

C34.81 is the ICD-10-CM diagnosis code for malignant neoplasm of overlapping sites of right bronchus and lung. Cancer that involves multiple areas of the right lung and/or right bronchus. C34.81 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, C34.81 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, C34.81 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.

This code indicates right-sided disease affecting more than one lobe or region. Because C34.81 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 C34.81 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •This code indicates right-sided disease affecting more than one lobe or region
  • •Document which specific lobes or areas are involved to support medical necessity and treatment planning

Clinical Significance

Right-sided overlapping lung cancer indicates locally advanced disease crossing anatomical boundaries within the right lung. This may include bilobar disease (e.g., upper and middle lobe) or tumor extending from the bronchus into parenchyma. These patients often require extended surgical resections such as bilobectomy or pneumonectomy.

Documentation Requirements

  • ✓Imaging showing tumor involvement of multiple right lung regions
  • ✓Pathology confirming single primary neoplasm crossing anatomical boundaries
  • ✓Documentation of which specific right-sided sites are involved
  • ✓TNM staging and surgical resection planning
  • ✓Molecular markers for treatment decisions

Commonly Confused Codes

  • •C34.82: Overlapping left lung: Verify right laterality
  • •C34.80: Overlapping, unspecified side: Use C34.81 when right side is documented
  • •C34.11/C34.2/C34.31: Single lobe codes: Use when the primary site is identifiable despite extension
  • •C34.91: Right lung, unspecified part: C34.81 is more specific with overlapping site information

Child Codes

C34.80Malignant neoplasm of overlapping sites of unspecified bronchus and lung
HCC 20
C34.81Malignant neoplasm of overlapping sites of right bronchus and lung
HCC 20
C34.82Malignant neoplasm of overlapping sites of left bronchus and lung
HCC 20

Code Hierarchy

└C34Malignant neoplasm of bronchus and lung└C34.8Malignant neoplasm of overlapping sites of bronchus and lung└C34.81Malignant neoplasm of overlapping sites of right bronchus and lung
└C34.81Malignant neoplasm of overlapping sites of right bronchus and lung

Because C34.81 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.

C34.81 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. Because C34.81 carries a payment HCC, you can see what it adds to a RAF score and check the documentation the chart needs before it is submitted.

More on C34.81

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