Recognizing Airspace Versus Interstitial Lung Disease–Flashcards

Question-and-answer flashcards covering key imaging features, etiologies, and diagnostic clues for airspace versus interstitial lung disease based on the lecture notes.

What are the two main radiographic patterns of parenchymal lung disease?

Airspace (alveolar) disease and interstitial (infiltrative) disease.

How do opacities of airspace disease typically appear on imaging?

Fluffy, cloud-like, hazy opacities with indistinct margins that often blend together (confluent).

Which imaging sign is almost always indicative of airspace disease?

An air bronchogram.

Define an air bronchogram.

Visible air-filled bronchi outlined by surrounding fluid or soft-tissue–filled alveoli.

List three acute causes of airspace disease.

Pneumonia, pulmonary alveolar edema, and pulmonary hemorrhage (others: aspiration, near-drowning).

What classic radiographic pattern is seen in pulmonary alveolar edema?

Bilateral perihilar "bat-wing" or "angel-wing" airspace opacities.

Why are air bronchograms usually absent in pulmonary alveolar edema?

Edema fluid fills both alveoli and bronchi, eliminating the air-to-fluid contrast needed for an air bronchogram.

Which lobe is most commonly involved in aspiration pneumonia in bedridden patients and why?

The right lower lobe because the right main bronchus is wider and more vertical.

What is the silhouette sign?

Loss of the normal edge between two contacting structures of the same radiographic density (e.g., fluid and soft tissue).

How does the silhouette sign assist in localizing lung disease?

By showing which normal structure the opacity abuts and silhouettes, revealing its lobar location.

Name four substances that can replace air in the alveoli to create airspace disease.

Fluid, blood, gastric contents, inflammatory exudate, or water.

Describe the three basic patterns of interstitial lung disease.

Reticular (network of lines), nodular (dots), and reticulonodular (combination of lines and dots).

Give four classic radiologic findings of pulmonary interstitial edema.

Kerley B lines, peribronchial cuffing, fluid in the fissures, and pleural effusions.

What condition is considered the precursor to pulmonary alveolar edema?

Pulmonary interstitial edema.

On CT, which three features are diagnostic of usual interstitial pneumonia (UIP)?

Subpleural reticular opacities at lung bases, honeycombing, and traction bronchiectasis.

Which patient group most commonly develops UIP?

Older men, often with a history of cigarette smoking or gastroesophageal reflux.

What CT finding helps distinguish nonspecific interstitial pneumonia (NSIP) from UIP?

Basilar ground-glass opacities frequently with subpleural sparing and minimal honeycombing.

Which connective-tissue disease is strongly associated with an NSIP pattern?

Scleroderma.

Name the four major histologic types of bronchogenic carcinoma.

Adenocarcinoma, squamous cell carcinoma, small cell carcinoma, and large cell carcinoma.

Which lung cancer type most often appears as a solitary peripheral nodule?

Adenocarcinoma.

What does spiculation around a pulmonary nodule on CT suggest?

Malignancy, such as bronchogenic carcinoma.

What are "cannonball" metastases?

Multiple large, rounded pulmonary nodules from hematogenous spread of a malignancy.

Give three primary tumors that commonly produce hematogenous pulmonary metastases.

Breast carcinoma, colorectal carcinoma, and renal cell carcinoma (others: bladder, testicular, sarcoma, melanoma).

How can lymphangitic carcinomatosis mimic congestive heart failure on imaging?

It shows Kerley lines, septal thickening, fissural fluid, and pleural effusions but is often limited to one lung or lobe.

Describe the typical progression of thoracic sarcoidosis on imaging.

Stage I: bilateral hilar/right paratracheal adenopathy; Stage II: adenopathy + interstitial lung disease; Stage III: interstitial disease without adenopathy; Stage IV: pulmonary fibrosis.

Approximately what percentage of community-acquired lobar pneumonia is due to Streptococcus pneumoniae?

About 90 %.

How rapidly can pneumococcal pneumonia clear radiographically after treatment?

Sometimes within 48 hours.

What is a Kerley B line?

A short, horizontal peripheral septal line representing fluid in thickened interlobular septa.

If extensive interstitial disease appears confluent on a chest radiograph, how can one avoid mistaking it for airspace disease?

Examine the peripheral margins for discrete lines/dots or obtain a CT scan for clarification.

What are the characteristic imaging findings of miliary tuberculosis?

Innumerable 1–3 mm nodules uniformly distributed throughout both lungs.

Does miliary tuberculosis usually heal with calcifications?

No; miliary TB seldom heals with calcification.

Which lung segments are most often involved in postprimary (reactivation) tuberculosis?

The apical and posterior segments of the upper lobes and the superior segments of the lower lobes.

Describe the typical appearance of a tuberculous cavity.

Thin-walled, smooth inner margin, usually without an air-fluid level.

What finding suggests transbronchial spread of tuberculosis?

An upper-lobe cavitary lesion accompanied by new airspace disease in another lobe or the opposite lung.

What is a tuberculoma?

A solitary pulmonary nodule of tuberculosis, often with nearby small satellite nodules.

Why are pleural effusions in postprimary TB clinically concerning?

They usually represent empyema from direct spread into the pleural space and carry a worse prognosis.

Name three diseases other than TB that can produce a miliary lung pattern.

Histoplasmosis, sarcoidosis, and silicosis.

How do the margins of airspace and interstitial opacities differ?

Airspace opacities have fuzzy, indistinct margins; interstitial lesions have sharp, discrete edges.

Why are normal bronchi usually invisible on chest radiographs?

Their thin walls contain air and are surrounded by aerated lung, providing no density contrast.

What is the clinical value of distinguishing airspace from interstitial patterns?

It narrows the differential diagnosis and guides appropriate management decisions.