Legionnaire's pneumonia: is there really an interstitial disease?

Area of Science:

• Radiology
• Infectious Diseases
• Pulmonology

Background:

• Legionella pneumonia is often termed "atypical pneumonia," implying interstitial chest X-ray findings.
• This classification may not accurately reflect the typical radiological presentation of Legionella pneumophila infections.

Purpose of the Study:

• To evaluate the consistency of radiological findings in Legionella pneumonia with the "atypical pneumonia" classification.
• To clarify the characteristic chest X-ray patterns associated with Legionella pneumophila community-acquired pneumonia.

Main Methods:

• Retrospective analysis of 18 patient cases with Legionella pneumophila pneumonia.
• Literature review of radiological findings in similar cases.
• Consensus review of chest X-rays by radiologists and a physician.

Main Results:

• Chest X-rays predominantly showed confluent (n=16) or patchy (n=7) infiltrates, with only one interstitial case.
• Lower lung fields were most commonly affected (n=15).
• Radiological findings sometimes worsened, with new patchy infiltrates and pleural effusions observed.

Conclusions:

• Radiological findings in Legionella pneumonia, characterized by confluent or patchy infiltrates, do not align with the typical "interstitial" pattern of "atypical pneumonia."
• The term "atypical pneumonia" should be reserved for clinical and microbiological contexts, not radiological descriptions of Legionella.
• Revised radiologic terminology is suggested for Legionella pneumonia to better reflect its presentation.