What is ICD-10 code J43.0?

J43.0 is the ICD-10-CM diagnosis code for Unilateral pulmonary emphysema [MacLeod's syndrome]. A condition where one lung develops abnormal air-filled spaces (emphysema) while the other lung remains relatively normal, often appearing as a collapsed lung on imaging. J43.0 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. J43.0 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. J43.0 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. J43.0 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 J43.0 map to under V28?

J43.0 maps to CMS-HCC V28 280 (Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders). The category number and label come from the CMS-HCC V28 model file for payment year 2026.

What does J43.0 pay in RAF?

J43.0 carries a community, non-dual, aged (CNA) RAF weight of 0.319 under CMS-HCC V28 for payment year 2026. The weight comes from the CMS V28 relative-factor file, not a hand-typed table.

What is the V28 vs V24 difference for J43.0?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. For J43.0, V28 maps to Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders at RAF 0.319 while V24 mapped to Chronic Obstructive Pulmonary Disease at RAF 0.335. Both models can still appear in legacy data and in payer-specific lookback periods.

What documentation supports J43.0?

Specify laterality (right or left) if the documentation indicates which lung is affected This is also known as MacLeod's syndrome and may be associated with childhood infections or unilateral lung hypoplasia Because J43.0 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. See the MEAT criteria checklist at /meat-criteria for what Monitor, Evaluate, Assess, or Treat looks like in a note. MEAT is generic documentation evidence, not a payer-specific rule.

2026 ICD-10-CM J43.0: Unilateral pulmonary

J43.0 maps to CMS-HCC V28 280 (RAF 0.319). Documentation must support MEAT. MEAT criteria · RAF calculator · HCC coding software

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Code lookupJ43.0Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the respiratory system (J00-J99) / Chronic lower respiratory diseases (J40-J4A)

J43.0

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

Unilateral pulmonary emphysema [MacLeod's syndrome]

A condition where one lung develops abnormal air-filled spaces (emphysema) while the other lung remains relatively normal, often appearing as a collapsed lung on imaging.

Buddy Insight

CMS-HCC V28

Mapped

HCC 280

Chronic Obstructive Pulmonary...

RAF 0.319

CMS-HCC V24

Mapped

HCC 111

Chronic Obstructive Pulmonary...

RAF 0.335

ACA/HHS

Mapped

HCC 160

HHS-HCC 160

Varies by metal level

ESRD/PACE

Mapped

HCC 111

Chronic Obstructive Pulmonary...

RAF 0.058

RXHCC

Mapped

HCC 229

COPD and Chronic Bronchitis

RAF 0.237

Code Book Path

Official

J43Emphysema

J43.0Unilateral pulmonary emphysema [MacLeod's syndrome]

Inclusion Terms

Official

Swyer-James syndrome
Unilateral emphysema
Unilateral hyperlucent lung
Unilateral pulmonary artery functional hypoplasia
Unilateral transparency of lung

Excludes 2

Official

emphysema due to inhalation of chemicals, gases, fumes or vapors (J68.4)
emphysema with chronic (obstructive) bronchitis (J44.-)
emphysematous (obstructive) bronchitis (J44.-)
traumatic subcutaneous emphysema (T79.7)

Related Child Codes

Official

J43.1Panlobular emphysema

J43.2Centrilobular emphysema

J43.8Other emphysema

J43.9Emphysema, unspecified

Includes

Official

ICD-10-CM does not list Includes notes for J43.0 in this effective period.

Excludes 1

Official

compensatory emphysema (J98.3)
interstitial emphysema (J98.2)
mediastinal emphysema (J98.2)
neonatal interstitial emphysema (P25.0)
surgical (subcutaneous) emphysema (T81.82)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for J43.0 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for J43.0 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for J43.0 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Imaging (CT scan preferred) demonstrating unilateral hyperlucent lung with air trapping

Documentation specifying unilateral involvement and the affected side

Clinical history supporting MacLeod's/Swyer-James syndrome (often childhood respiratory infection)

Pulmonary function testing showing any obstructive pattern

MEAT Support

HCC Buddy guidance

Imaging (CT scan preferred) demonstrating unilateral hyperlucent lung with air trapping

Documentation specifying unilateral involvement and the affected side

Clinical history supporting MacLeod's/Swyer-James syndrome (often childhood respiratory infection)

Pulmonary function testing showing any obstructive pattern

Audit Caution

HCC Buddy guidance

Confusing MacLeod's syndrome with typical bilateral emphysema — this is a unilateral condition with a specific etiology

Using this code for unilateral bullous emphysema in a patient with otherwise bilateral disease

Not recognizing the rarity of this diagnosis and querying when it appears unexpectedly in documentation

Failing to code any coexisting COPD separately if the patient also has smoking-related obstructive disease

Common Mistakes

HCC Buddy guidance

J43.9 — Emphysema, unspecified: use when emphysema type is not specified; J43.0 is more specific

J43.1 — Panlobular emphysema: bilateral condition affecting lower lobes, typically alpha-1 antitrypsin deficiency

J43.2 — Centrilobular emphysema: bilateral upper-lobe predominant, typically smoking-related

J93.x — Pneumothorax: can mimic unilateral hyperlucency but is a different condition entirely

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 J43.0 an HCC code?

Yes. J43.0 (Unilateral pulmonary emphysema [MacLeod's syndrome]) maps to Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders under the CMS-HCC V28 risk adjustment model (and Chronic Obstructive Pulmonary Disease under V24), with a community non-dual aged RAF of 0.319. It is billable for payment year 2026.

Coder answer: J43.0 is billable and maps to V28 HCC 280, Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code: J43.0
Description: Unilateral pulmonary emphysema [MacLeod's syndrome]
HCC (V28): HCC 280 — Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders
RAF: 0.319
Billable: Yes
Payment year: 2026

HCC Category Mapping

V28HCC 280, Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders

0.319

V24HCC 111, Chronic Obstructive Pulmonary Disease

0.335

ESRDHCC 111, Chronic Obstructive Pulmonary Disease

0.058

RxHCCHCC 229, COPD and Chronic Bronchitis

0.237

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 J43.0 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for J43.0

For J43.0 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 J43.0 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

J43.0 is the ICD-10-CM diagnosis code for unilateral pulmonary emphysema [macleod's syndrome]. A condition where one lung develops abnormal air-filled spaces (emphysema) while the other lung remains relatively normal, often appearing as a collapsed lung on imaging. J43.0 sits in the ICD-10-CM chapter for diseases of the respiratory system (j00-j99), within the section covering chronic lower respiratory diseases (j40-j4a).

Under the CMS-HCC V28 risk adjustment model, J43.0 maps to Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders (HCC 280) with a community, non-dual, aged base RAF weight of 0.319. Under the older CMS-HCC V24 model, J43.0 maps to Chronic Obstructive Pulmonary Disease (HCC 111) with a community, non-dual, aged base RAF weight of 0.335. 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.

Specify laterality (right or left) if the documentation indicates which lung is affected. Because J43.0 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 J43.0 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Specify laterality (right or left) if the documentation indicates which lung is affected
•This is also known as MacLeod's syndrome and may be associated with childhood infections or unilateral lung hypoplasia

Clinical Significance

Unilateral pulmonary emphysema (MacLeod's syndrome, also known as Swyer-James syndrome) is a rare condition characterized by hyperlucency of one lung due to underdevelopment of pulmonary vasculature, typically following childhood bronchiolitis obliterans. This is distinct from typical smoking-related emphysema and represents a specific developmental/acquired lung abnormality.

Documentation Requirements

✓Imaging (CT scan preferred) demonstrating unilateral hyperlucent lung with air trapping
✓Documentation specifying unilateral involvement and the affected side
✓Clinical history supporting MacLeod's/Swyer-James syndrome (often childhood respiratory infection)
✓Pulmonary function testing showing any obstructive pattern
✓Current symptoms and functional impact
✓Differentiation from other causes of unilateral hyperlucency (pneumothorax, foreign body)

Commonly Confused Codes

•J43.9: Emphysema, unspecified: use when emphysema type is not specified; J43.0 is more specific
•J43.1: Panlobular emphysema: bilateral condition affecting lower lobes, typically alpha-1 antitrypsin deficiency
•J43.2: Centrilobular emphysema: bilateral upper-lobe predominant, typically smoking-related
•J93.x: Pneumothorax: can mimic unilateral hyperlucency but is a different condition entirely