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C34.92 ICD-10-CM Code: Malignant neoplasm of unspecified part of left bronchus or lung

C34.92 maps to CMS-HCC V28 20. A source-labeled RAF reference is available. Confirm the documented diagnosis and applicable coding requirements. MEAT criteria · RAF Calculator · free HCC coding tools

ICD-10-CM Code View

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Code lookupC34.92

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

C34.92

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

Malignant neoplasm of unspecified part of left bronchus or lung

Cancer that starts in the left lung or its main airway (bronchus), but the exact location within the left lung is not specified.

Buddy the Bee presenting code insight

Buddy Insight

Left-sided lung cancer without specified lobe provides laterality but lacks anatomical detail.

OverviewRisk ModelsCode BookDocumentationAuditNotesEdition comparison

CMS-HCC V28

HCC 20

Coefficient HCC 20: 1.136 (Community Non-Dual Aged (CNA))

CMS-HCC V24

Historical

Historical

Not used for CY2026 payment

ACA/HHS

HCC 009

Code-level coefficient reference

ESRD/PACE

HCC 9

Code-level coefficient reference

RXHCC

HCC 20

Code-level coefficient reference

Code Book Path

Official
C34Malignant neoplasm of bronchus and lungC34.9Malignant neoplasm of unspecified part of bronchus or lungC34.92Malignant neoplasm of unspecified part of left bronchus or lung

Inclusion Terms

Official

No inclusion terms are included in this display for C34.92. Check the code and parent instructions in the Code Book.

Excludes 2

Official

No Excludes 2 notes are included in this display for C34.92. Check the code and parent instructions in the Code Book.

Related Codes

Official
C34.90Malignant neoplasm of unspecified part of unspecified bronchus or lungC34.91Malignant neoplasm of unspecified part of right bronchus or lung

Includes

Official
  • malignant neoplasm of middle earInherited from C30-C39

Excludes 1

Official
  • mesothelioma (C45.-)Inherited from C30-C39, C34
  • Kaposi's sarcoma of lung (C46.5-)Inherited from C30-C39, C34
  • malignant carcinoid tumor of the bronchus and lung (C7A.090)Inherited from C30-C39, C34

Code First

Official

No Code First sequencing instructions are included in this display for C34.92. Check the code and parent instructions in the Code Book.

Use Additional

Official
  • code to identify:Inherited from C34
  • exposure to environmental tobacco smoke (Z77.22)Inherited from C34
  • exposure to tobacco smoke in the perinatal period (P96.81)Inherited from C34
  • history of tobacco dependence (Z87.891)Inherited from C34
  • occupational exposure to environmental tobacco smoke (Z57.31)Inherited from C34
  • tobacco dependence (F17.-)Inherited from C34
  • tobacco use (Z72.0)Inherited from C34

Code Also

Official

No Code Also instructions are included in this display for C34.92. Check the code and parent instructions in the Code Book.

Buddy Documentation Tip

HCC Buddy guidance
Clinical or pathological confirmation of left-sided lung malignancy
Evidence of provider query for lobar specificity
Imaging reviewed for lobe identification
Histological type and molecular markers

MEAT Support

HCC Buddy guidance
Clinical or pathological confirmation of left-sided lung malignancy
Evidence of provider query for lobar specificity
Imaging reviewed for lobe identification
Histological type and molecular markers

Audit Caution

HCC Buddy guidance
Not reviewing CT imaging that typically distinguishes left upper from left lower lobe
Using this code when pathology or surgical reports specify the lobe
Confusing lingular tumors with middle lobe — the left lung has no middle lobe
Not querying the provider for lobar detail when only two left lobes make identification straightforward

Common Mistakes

HCC Buddy guidance
C34.12 — Left upper lobe: Review imaging; includes lingular segment
C34.32 — Left lower lobe: Usually identifiable on CT
C34.90 — Unspecified lung: C34.92 provides laterality at minimum
C34.82 — Overlapping left lung: Use when multiple left-sided regions are clearly involved

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 C34.92 an HCC code?

Yes. C34.92 (Malignant neoplasm of unspecified part of left bronchus or lung) maps to HCC 20, Lung and Other Severe Cancers under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 1.136. 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: C34.92 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
C34.92
Description
Malignant neoplasm of unspecified part of left bronchus or lung
HCC (V28)
HCC 20 — Lung and Other Severe Cancers
RAF reference coefficient
1.136
Billable
Yes
Payment year
2026

HCC Category Mapping

V28HCC 20, Lung and Other Severe Cancers
1.136
ESRDHCC 9, Lung and Other Severe Cancers
Not separately weighted
RxHCCHCC 20, Lung, Kidney, and Other Cancers; Secondary Cancer of Lymph Nodes and Other Sites
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 C34.92 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT review for C34.92

For C34.92, 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

C34.92 is the ICD-10-CM diagnosis code for malignant neoplasm of unspecified part of left bronchus or lung. Cancer that starts in the left lung or its main airway (bronchus), but the exact location within the left lung is not specified. C34.92 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, C34.92 maps to Lung and Other Severe Cancers (HCC 20) with a source-labeled community, non-dual, aged reference coefficient of 1.136. No V24 mapping is shown for C34.92; 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.

Malignant neoplasm of unspecified part of left bronchus or lung, laterality captured, lobe unspecified. For C34.92, 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 C34.92 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Malignant neoplasm of unspecified part of left bronchus or lung, laterality captured, lobe unspecified.
  • •As with C34.91, lobe specification moves to the C34.12, C34.32, or C34.02 variants.

Clinical Significance

Left-sided lung cancer without specified lobe provides laterality but lacks anatomical detail. The left lung has two lobes (upper and lower), making lobar identification typically straightforward on imaging. Identifying the specific lobe affects surgical approach, as left upper lobectomy and left lower lobectomy have different anatomical considerations.

Documentation Requirements

  • ✓Clinical or pathological confirmation of left-sided lung malignancy
  • ✓Evidence of provider query for lobar specificity
  • ✓Imaging reviewed for lobe identification
  • ✓Histological type and molecular markers
  • ✓TNM staging and treatment plan

Commonly Confused Codes

  • •C34.12: Left upper lobe: Review imaging; includes lingular segment
  • •C34.32: Left lower lobe: Usually identifiable on CT
  • •C34.90: Unspecified lung: C34.92 provides laterality at minimum
  • •C34.82: Overlapping left lung: Use when multiple left-sided regions are clearly involved

Child Codes

C34.90Malignant neoplasm of unspecified part of unspecified bronchus or lung
HCC 20
C34.91Malignant neoplasm of unspecified part of right bronchus or lung
HCC 20
C34.92Malignant neoplasm of unspecified part of left bronchus or lung
HCC 20

Code Hierarchy

└C34Malignant neoplasm of bronchus and lung└C34.9Malignant neoplasm of unspecified part of bronchus or lung└C34.92Malignant neoplasm of unspecified part of left bronchus or lung
└C34.92Malignant neoplasm of unspecified part of left bronchus or lung

Also searched as

  • C34 92
  • C3492

For C34.92, 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.

C34.92 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. The mapping identifies a payment HCC category for C34.92. 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.

More on C34.92

Code family

Every C34 code with its CMS-HCC V28 statusMalignant neoplasm of bronchus and lung, 16 billable codes

Related condition guides

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