Acute drug-induced interstitial lung disorders

This code signifies an acute inflammatory reaction in the lung's interstitium, directly caused by an adverse drug effect. It encompasses conditions like drug-induced pneumonitis or hypersensitivity pneumonitis, where medication is the clear etiology. The damage is primarily to the lung tissue surrounding the air sacs, rather than the air sacs themselves.

Assign this code when documentation explicitly links an acute interstitial lung disorder to a specific medication. This includes cases where a patient develops new or worsening respiratory symptoms, imaging shows interstitial changes, and a drug is identified as the causative agent. Documentation should specify "drug-induced" and "acute" to support this diagnosis.

• Always identify the specific drug causing the reaction using an external cause code (T36-T50 with 5th or 6th character indicating adverse effect).
• Distinguish from chronic drug-induced interstitial lung disorders, which would be coded differently.
• Do not use if the documentation indicates lymphoid interstitial pneumonia or interstitial pneumonia NOS, as these are Excludes1 conditions.