ICD-10 Code J84.170 – Interstitial lung disease with progressive fibrotic phenotype in diseases classified elsewhere (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code J84.170 – Interstitial lung disease with progressive fibrotic phenotype in diseases classified elsewhere
What it is
This code identifies interstitial lung disease that shows a progressive fibrotic pattern and is coded elsewhere because the underlying cause is classified in another category. It reflects worsening lung scarring over time.
Clinical signs
Clinical features vary; refer to documentation. Commonly documented findings include chronic dyspnea, cough, reduced exercise tolerance, and imaging or specialist notes describing progressive fibrosis.
When to use this code
Use this code when the record clearly states interstitial lung disease with a progressive fibrotic phenotype and the condition is classified elsewhere. It is appropriate when the clinician documents progression of fibrotic change rather than a nonspecific interstitial lung disease alone. Confirm the underlying disease is coded separately when required.
Do not use for
Do not use it for interstitial lung disease without documented progressive fibrotic behavior. Do not assign it if the record only mentions pulmonary fibrosis, interstitial changes, or an unspecified lung disorder; check documentation.
Coding tip
Look for wording such as “progressive fibrotic phenotype” and code the underlying disease first if the note identifies one.