What are Pulmonary Infiltrates?

Photo credit: The Regents of the University of California.

Infiltrates is a term commonly used to describe findings on chest x-ray, but what does it mean?

Simply put it is defined as: “The accumulation of foreign and/or abnormal substances (i.e pus, blood, fluid) within body tissues or cells“. In the context of a chest x-ray, this typically refers to accumulation within the alveoli or interstitium.

It will be differentiated into “alveolar infiltrates” (think airspace disease) or “interstitial infiltrates” (think congestive heart failure); though there are many other causes.

Interstitial Infiltrates	Alveolar Infiltrates
Pulmonary edema (most common, e.g. Left Congestive Heart Failure) Mitral Stenosis Lymphangitic carcinoma Lymphoma Mycoplasma pneumonia or Viral Pneumonia Sarcoidosis Idiopathic Pulmonary Fibrosis Hemosiderosis (late findings)	Typically signs of airspace disease within the parenchyma Segmental distribution of Pulmonary Infiltrate Coalescence of infiltrates Fluffy margins Air Bronchograms Rosette Patterns Silhouetting of normal structures

References

1. fpnotebook.com

2. radiopaedia.org