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J84.170 ICD-10-CM Code: Interstitial lung disease with progressive fibrotic phenotype in diseases classified elsewhere

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

J84.170

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

Interstitial lung disease with progressive fibrotic phenotype in diseases classified elsewhere

Progressive scarring of lung tissue that develops as part of another disease, leading to worsening lung function over time.

Buddy the Bee presenting code insight

Buddy Insight

Interstitial lung disease with progressive fibrotic phenotype represents a subset of ILDs that behave like IPF with relentless fibrotic progression despite treatment.

CMS-HCC V28

HCC 278

RAF 0.818

CMS-HCC V24

HCC 112

RAF 0.219

ACA/HHS

HCC 162

Varies by metal level

ESRD/PACE

HCC 112

RAF 0.058

RXHCC

HCC 226

RAF 4.862

Code Book Path

Official
J84.1Other interstitial pulmonary diseases with fibrosis
J84.17Other interstitial pulmonary diseases with fibrosis in diseases classified elsewhere
J84.170Interstitial lung disease with progressive fibrotic phenotype in diseases classified elsewhere

Inclusion Terms

Official
  • Progressive fibrotic interstitial lung disease

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for J84.170 in this effective period.

Related Child Codes

Official
J84.178Other interstitial pulmonary diseases with fibrosis in diseases classified elsewhere

Includes

Official

ICD-10-CM does not list Includes notes for J84.170 in this effective period.

Excludes 1

Official

ICD-10-CM does not list Excludes 1 notes for J84.170 in this effective period.

Code First

Official
  • underlying disease, such as:
  • lung diseases due to external agents (J60-J70)
  • rheumatoid arthritis (M05.00-M06.9)
  • sarcoidosis (D86.-)
  • systemic connective tissue disorders (M30-M36)

Use Additional

Official

ICD-10-CM does not list Use Additional Code instructions for J84.170 in this effective period.

Code Also

Official

ICD-10-CM does not list Code Also instructions for J84.170 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance
Documentation of the underlying disease classified elsewhere (e.g., rheumatoid arthritis-ILD, hypersensitivity pneumonitis, sarcoidosis)
Evidence of progressive fibrotic phenotype: declining forced vital capacity, worsening fibrosis on serial imaging, or worsening symptoms despite treatment
Serial imaging (high-resolution computed tomography) showing progressive fibrotic changes over time
Pulmonary function test trends demonstrating decline

MEAT Support

HCC Buddy guidance
Documentation of the underlying disease classified elsewhere (e.g., rheumatoid arthritis-ILD, hypersensitivity pneumonitis, sarcoidosis)
Evidence of progressive fibrotic phenotype: declining forced vital capacity, worsening fibrosis on serial imaging, or worsening symptoms despite treatment
Serial imaging (high-resolution computed tomography) showing progressive fibrotic changes over time
Pulmonary function test trends demonstrating decline

Audit Caution

HCC Buddy guidance
Using this as a primary/principal diagnosis — it must be coded secondary to the underlying disease
Failing to code the underlying condition (e.g., rheumatoid arthritis, sarcoidosis) as the first-listed diagnosis
Confusing with primary IPF (J84.112) — this code is specifically for progressive fibrosis in OTHER diseases
Assigning this code without documentation of progressive decline (declining PFTs, worsening imaging) over time

Common Mistakes

HCC Buddy guidance
J84.112 — Idiopathic pulmonary fibrosis is a primary diagnosis; J84.170 is used when progressive fibrosis occurs in OTHER classified diseases
J84.178 — Other interstitial pulmonary diseases with fibrosis in diseases classified elsewhere covers fibrosis WITHOUT the progressive phenotype
J84.10 — Pulmonary fibrosis unspecified does not capture the progressive nature or the secondary relationship
J84.111 — Idiopathic interstitial pneumonia NOS does not specify the progressive fibrotic behavior

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 J84.170 an HCC code?

Yes. J84.170 (Interstitial lung disease with progressive fibrotic phenotype in diseases classified elsewhere) maps to Idiopathic Pulmonary Fibrosis and Lung Involvement in Systemic Sclerosis under the CMS-HCC V28 risk adjustment model (and Fibrosis of Lung and Other Chronic Lung Disorders under V24), with a community non-dual aged RAF of 0.818. It is billable for payment year 2026.

Coder answer: J84.170 is billable and maps to V28 HCC 278, Idiopathic Pulmonary Fibrosis and Lung Involvement in Systemic Sclerosis. Open it in the Code Book for the tabular path, RAF, and MEAT checklist.

Code
J84.170
Description
Interstitial lung disease with progressive fibrotic phenotype in diseases classified elsewhere
HCC (V28)
HCC 278 — Idiopathic Pulmonary Fibrosis and Lung Involvement in Systemic Sclerosis
RAF
0.818
Billable
Yes
Payment year
2026

HCC Category Mapping

V28HCC 278, Idiopathic Pulmonary Fibrosis and Lung Involvement in Systemic Sclerosis
0.818
V24HCC 112, Fibrosis of Lung and Other Chronic Lung Disorders
0.219
ESRDHCC 112, Fibrosis of Lung and Other Chronic Lung Disorders
0.058
RxHCCHCC 226, Fibrosis of Lung and Other Chronic Lung Disorders
4.862

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 J84.170 in the Code Book — tabular path, V28 RAF, and MEAT checklist →

MEAT Criteria for J84.170

For J84.170 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 J84.170 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

J84.170 is the ICD-10-CM diagnosis code for interstitial lung disease with progressive fibrotic phenotype in diseases classified elsewhere. Progressive scarring of lung tissue that develops as part of another disease, leading to worsening lung function over time. J84.170 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, J84.170 maps to Idiopathic Pulmonary Fibrosis and Lung Involvement in Systemic Sclerosis (HCC 278) with a community, non-dual, aged base RAF weight of 0.818. Under the older CMS-HCC V24 model, J84.170 maps to Fibrosis of Lung and Other Chronic Lung Disorders (HCC 112) with a community, non-dual, aged base RAF weight of 0.219. 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.

Always code the underlying disease first, then use this code as a secondary diagnosis. Because J84.170 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 J84.170 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

  • •Always code the underlying disease first, then use this code as a secondary diagnosis
  • •Ensure documentation clearly indicates progressive fibrotic phenotype

Clinical Significance

Interstitial lung disease with progressive fibrotic phenotype represents a subset of ILDs that behave like IPF with relentless fibrotic progression despite treatment. This is a high-severity manifestation code used as a secondary diagnosis alongside the underlying condition. The progressive fibrotic phenotype indicates patients eligible for antifibrotic therapy regardless of their underlying ILD, reflecting very high resource utilization.

Documentation Requirements

  • ✓Documentation of the underlying disease classified elsewhere (e.g., rheumatoid arthritis-ILD, hypersensitivity pneumonitis, sarcoidosis)
  • ✓Evidence of progressive fibrotic phenotype: declining forced vital capacity, worsening fibrosis on serial imaging, or worsening symptoms despite treatment
  • ✓Serial imaging (high-resolution computed tomography) showing progressive fibrotic changes over time
  • ✓Pulmonary function test trends demonstrating decline
  • ✓Code the underlying disease first, then J84.170 as a secondary/manifestation code

Code First

  • underlying disease, such as:
  • lung diseases due to external agents (J60-J70)
  • rheumatoid arthritis (M05.00-M06.9)
  • sarcoidosis (D86.-)
  • systemic connective tissue disorders (M30-M36)

Commonly Confused Codes

  • •J84.112: Idiopathic pulmonary fibrosis is a primary diagnosis; J84.170 is used when progressive fibrosis occurs in OTHER classified diseases
  • •J84.178: Other interstitial pulmonary diseases with fibrosis in diseases classified elsewhere covers fibrosis WITHOUT the progressive phenotype
  • •J84.10: Pulmonary fibrosis unspecified does not capture the progressive nature or the secondary relationship
  • •J84.111: Idiopathic interstitial pneumonia NOS does not specify the progressive fibrotic behavior

Child Codes

J84.170Interstitial lung disease with progressive fibrotic phenotype in diseases classified elsewhere
HCC 278
J84.178Other interstitial pulmonary diseases with fibrosis in diseases classified elsewhere
HCC 280

Code Hierarchy

└J84Other interstitial pulmonary diseases└J84.1Other interstitial pulmonary diseases with fibrosis└J84.17Other interstitial pulmonary diseases with fibrosis in diseases classified elsewhere└J84.170Interstitial lung disease with progressive fibrotic phenotype in diseases classified elsewhere
└J84.170Interstitial lung disease with progressive fibrotic phenotype in diseases classified elsewhere

J84.170 code history

Code setChange
FY2021 (effective Oct 1, 2020)Added to the code set

Source: official CMS ICD-10-CM order and addenda files, FY2016 through FY2027.

Because J84.170 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.

J84.170 maps to CMS-HCC V28 category 278, Idiopathic Pulmonary Fibrosis and Lung Involvement in Systemic Sclerosis. See the ICD-10 to HCC mapping hub for how the V28 crosswalk works. Because J84.170 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.

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Open J84.170 in the Code Book for the full Index-to-Tabular path, MEAT checklist, and V28 HCC mapping, or in the Encoder to code from a keyword search. Pro includes 7 days to try everything, no card required.

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