TB, Lung Abscess, and Cystic Fibrosis

TB, Lung Abscess, and Cystic Fibrosis

TB • Radiographic findings in primary TB are Nonspecific • Tends to like the lower lung zones • Cavitation is not as common in primary TB as in reactivation TB • However lymphadenopathy is a common finding in primary TB and uncommon in reactivation TB

TB • Patchy left lower lobe opacity • Looks like pneumonia

TB • Right upper and lower lobe consolidation • Right pleural effusion

TB • Cavitary right upper lobe lesion • Right paratracheal lymphadenopathy • Right middle lobe infiltrate • Notice the ipsilateral lymphadenopathy

TB • Thick walled cavity with satellite nodules • Smooth inner wall

TB • Focal right middle lobe infiltrate • Nodular like infiltrate • Endobronchial spread of TB • Adjacent areas of lung are infected by bronchial secretions

TB • Radiographic findings usually present 2 years after initial infection • Infiltrates usually like the apical and posterior segments of upper lobes and superior segment of lower lobes

TB • CT scan through the upper chest shows a thick walled cavity with an air fluid level and surrounding infiltrate • Cavities result from caseous necrosis

TB • Complications of TB cavities • Mycetoma “fungus ball” • Rasmussen Aneurysm which is weakening of bronchial artery adjacent to a cavitary lesion

Rasmussen Aneurysm

TB • Bilateral lung nodules resulting from endobronchial spread of TB • Right upper lobe cavity

Miliary TB • Right paratracheal lymphadenopathy • Bilateral tiny uniform nodules • Diffuse pattern of nodules is due to hematogenous spread

Miliary TB

TB Key Points • Imaging findings of primary TB are nonspecific • Primary TB differentiated from bacterial pneumonia by the presence of lymphadenopathy • Reactivation TB recognized by fibrocavitary disease and a history of prior exposure

TB Key Points • Inactive disease cannot be established without prior films • Primary TB tends to affect the lower lung zones while reactivation TB tends to affect the upper lung zones

Pneumococcal PNA • • • •

Complications Lung necrosis Abscess formation Often need clinical history to distinguish from TB

Lung Abscess • Air fluid level within a large cavity • Can communicate with the pleura resulting in an empyema

Lung Abscess

Lung Abscess • 54 year old male with cough and foul smelling sputum • Cavity within the superior segment of the left lower lobe • Common site for aspiration

Lung Abscess • Irregular cavity • Typically more posterior • Often has an air/fluid level within it • Often has surrounding infiltrate

Lung Abscess • Cavity with air fluid level and foul smelling sputum • Anaerobic organisms often the cause of abscesses from aspiration

Lung Abscess Key Points • Typical radiographic appearance is an irregular cavity with an air fluid level • Lung abscesses from aspiration often occur in the posterior segments of upper lobes or superior segments of lower lobes • The wall thickness of lung abscesses progresses from thick to thin and irregular to well circumscribed

Cystic Fibrosis • Abnormal sodium/chloride transport in exocrine tissues • Results in thick viscous mucus • Obstructs airways resulting in repeat infections and colonization • Airways dilate and cysts form from air trapping • Scarring from the repeated infections

Cystic Fibrosis • Hyperinflation • Upper lobe bronchiectasis • Tram tracking