What is ICD-10 code J84.02?

J84.02 is the ICD-10-CM diagnosis code for Pulmonary alveolar microlithiasis. A rare inherited lung disease where tiny mineral deposits accumulate in the lungs, causing progressive breathing problems. It belongs to the ICD-10-CM chapter for diseases of the respiratory system (j00-j99). J84.02 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. J84.02 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. J84.02 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. J84.02 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 J84.02 map to under V28?

J84.02 maps to CMS-HCC V28 HCC 280 (Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders). The category numbers, labels, and conditions come from the CMS-HCC V28 model file for payment year 2026.

2026 ICD-10-CM J84.02: Pulmonary alveolar

J84.02 maps to CMS-HCC V28 280. A source-labeled RAF reference is available. Documentation must support MEAT. MEAT criteria · RAF Calculator · free HCC coding tools

ICD-10-CM Code View

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Code lookupJ84.02Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the respiratory system (J00-J99) / Other respiratory diseases principally affecting the interstitium (J80-J84)

J84.02

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

Pulmonary alveolar microlithiasis

A rare inherited lung disease where tiny mineral deposits accumulate in the lungs, causing progressive breathing problems.

Buddy Insight

Pulmonary alveolar microlithiasis is a rare genetic lung disease characterized by progressive intra-alveolar calcium phosphate microliths.

CMS-HCC V28

Mapped

HCC 280

Chronic Obstructive Pulmonary...

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 162

HHS-HCC 162 adult, RAF varies...

Code-level coefficient reference

ESRD/PACE

Mapped

HCC 112

Fibrosis of Lung and Other Ch...

Code-level coefficient reference

RXHCC

Mapped

HCC 227

Pulmonary Fibrosis, Except Id...

Code-level coefficient reference

Code Book Path

Official

J84Other interstitial pulmonary diseases

J84.0Alveolar and parieto-alveolar conditions

J84.02Pulmonary alveolar microlithiasis

Inclusion Terms

Official

ICD-10-CM does not list inclusion terms for J84.02 in this effective period.

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for J84.02 in this effective period.

Related Child Codes

Official

J84.01Alveolar proteinosis

J84.03Idiopathic pulmonary hemosiderosis

J84.09Other alveolar and parieto-alveolar conditions

Includes

Official

ICD-10-CM does not list Includes notes for J84.02 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for J84.02 in this effective period.

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for J84.02 in this effective period.

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for J84.02 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for J84.02 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Chest imaging showing characteristic 'sandstorm' appearance with diffuse bilateral calcifications

Family history of pulmonary alveolar microlithiasis (autosomal recessive inheritance, SLC34A2 gene mutations)

Pulmonary function test results documenting restrictive defect progression

Clinical assessment of disease severity and oxygen requirements

MEAT Support

HCC Buddy guidance

Chest imaging showing characteristic 'sandstorm' appearance with diffuse bilateral calcifications

Family history of pulmonary alveolar microlithiasis (autosomal recessive inheritance, SLC34A2 gene mutations)

Pulmonary function test results documenting restrictive defect progression

Clinical assessment of disease severity and oxygen requirements

Audit Caution

HCC Buddy guidance

Not recognizing this rare condition when diffuse bilateral pulmonary calcifications are seen on imaging

Confusing the calcified opacities with metastatic calcification from hypercalcemia — different etiology and coding

Using generic interstitial lung disease codes when the specific microlithiasis diagnosis is established

Not documenting the genetic/familial nature of the disease for complete clinical context

Common Mistakes

HCC Buddy guidance

J84.01 (Alveolar proteinosis) — proteinaceous material vs. mineral deposits in alveoli

J84.10 (Pulmonary fibrosis, unspecified) — microlithiasis is not primarily fibrotic

J63.4 (Siderosis) — iron deposits from occupational exposure vs. calcium phosphate deposits from genetic disease

J84.09 (Other alveolar and parieto-alveolar conditions) — use J84.02 specifically for microlithiasis

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 J84.02 an HCC code?

Yes. J84.02 (Pulmonary alveolar microlithiasis) maps to HCC 280, Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders under the CMS-HCC V28 risk adjustment model, with a source-labeled community non-dual aged reference coefficient of 0.319. 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: J84.02 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: J84.02
Description: Pulmonary alveolar microlithiasis
HCC (V28): HCC 280 — Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders
RAF reference coefficient: 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

ESRDHCC 112, Fibrosis of Lung and Other Chronic Lung Disorders

Not separately weighted

RxHCCHCC 227, Pulmonary Fibrosis, Except Idiopathic

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 J84.02 in the Code Book — tabular path, V28 RAF reference, and MEAT checklist →

MEAT Criteria for J84.02

For J84.02 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 J84.02 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

J84.02 is the ICD-10-CM diagnosis code for pulmonary alveolar microlithiasis. A rare inherited lung disease where tiny mineral deposits accumulate in the lungs, causing progressive breathing problems. J84.02 sits in the ICD-10-CM chapter for diseases of the respiratory system (j00-j99), within the section covering other respiratory diseases principally affecting the interstitium (j80-j84).

Under the CMS-HCC V28 risk adjustment model, J84.02 maps to Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders (HCC 280) with a source-labeled community, non-dual, aged reference coefficient of 0.319. No V24 mapping is shown for J84.02; use the applicable model and payment year when reviewing the V28 mapping. 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. 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.

This is a genetic condition; document family history if available. Because J84.02 maps to an HCC category, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) before the diagnosis is used for risk adjustment. 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 J84.02 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•This is a genetic condition; document family history if available
•Verify imaging findings support the diagnosis of microlithiasis

Clinical Significance

Pulmonary alveolar microlithiasis is a rare genetic lung disease characterized by progressive intra-alveolar calcium phosphate microliths. It is significant for risk adjustment because it can progress to respiratory failure over years to decades, requiring long-term monitoring, and in severe cases, lung transplantation evaluation.

Documentation Requirements

✓Chest imaging showing characteristic 'sandstorm' appearance with diffuse bilateral calcifications
✓Family history of pulmonary alveolar microlithiasis (autosomal recessive inheritance, SLC34A2 gene mutations)
✓Pulmonary function test results documenting restrictive defect progression
✓Clinical assessment of disease severity and oxygen requirements
✓Genetic testing results if performed
✓Treatment plan and transplant evaluation status if applicable

Commonly Confused Codes

•J84.01 (Alveolar proteinosis): proteinaceous material vs. mineral deposits in alveoli
•J84.10 (Pulmonary fibrosis, unspecified): microlithiasis is not primarily fibrotic
•J63.4 (Siderosis): iron deposits from occupational exposure vs. calcium phosphate deposits from genetic disease
•J84.09 (Other alveolar and parieto-alveolar conditions): use J84.02 specifically for microlithiasis