Cavitary Lung Disease
Cavitary lung diseases may arise from a broad range of disease processes.
Cavitation may represent an active, latent, or resolved condition.
Pathologic definition: air-filled spaces within a nodule, mass, or area of consolidation produced by expulsion of the necrotic debris via the bronchiolar tree.
Radiologic definition: lucent areas within the lung that may or may not contain an air–fluid level that is surrounded by a wall, usually of varied thickness.
Other conditions such as cysts, bullae, and pneumatoceles may be incorrectly referred to as cavities.
The epidemiology of cavitary lung disease is related to the epidemiology of the underlying disease process.
There is limited data on what the incidence of cavitation by itself is in the overall population.
The differential diagnosis of cavitary lung lesions is presented in Table 28-1.
Necrotizing pneumonia can lead to cavitation in the setting of (or after) an acute febrile illness with productive cough.
Pyogenic abscesses develop as the ongoing infection destroys the surrounding lung parenchyma. Liquefaction necrosis and communication with the airways may develop, which leads to evacuation and expectoration of the abscess fluid, thereby producing a cavity.
Causative organisms commonly include:
Staphylococcus aureus, Klebsiella, Legionella, and other gram-negative bacteria (Pseudomonas, Escherichia coli, Proteus, and Serratia).1
Anaerobes and mixed gram-negative organisms are more common with comorbid risk factors such as alcoholism, poor dentition, existence of otolaryngologic pathology, and aspiration pneumonia.
It is rare for pneumonias caused by Mycoplasma, Chlamydia psittaci, viruses, Streptococcus pneumoniae, or Haemophilus influenzae to produce cavitary lesions, although these bacteria may still be cultured from airway secretions.
TB: cavitation is found in most cases of reactivation TB and in ∼10% of primary cases.
The most common non-TB mycobacterial organisms are Mycobacterium aviumintracellulare complex and M. kansasii.
Coccidioidomycosis: a common fungal pathogen associated with cavitary lung diseases. Endemic to the southwestern United States, Mexico, and Central and South America. Lives in the soil, and infectious airborne spores are transmitted via inhalation.3
TABLE 28-1 DIFFERENTIAL DIAGNOSIS OF CAVITARY LUNG DISEASE
Klebsiella, Legionella, and other gram-negative bacteria (e.g., Pseudomonas, Escherichia coli, Proteus, and Serratia)
Atypical mycobacteria (e.g., M. avium complex and M. kansasii)
Coccidioidomycosis, histoplasmosis, blastomycosis, aspergillosis, cryptococcosis, actinomycosis, sporotrichosis, mucormycosis, and invasive candidiasis
Pneumocystis jirovecii, echinococcosis (hydatid disease), amebiasis, paragonimiasis
Primary (particularly squamous cell bronchogenic carcinoma)
Lymphoma (Hodgkin or non-Hodgkin)
Granulomatosis with polyangiitis
Thromboembolic (pulmonary emboli, infective endocarditis/septic emboli)
Congenital adenomatoid malformation
Pulmonary Langerhans cell histiocytosis
Histoplasmosis: found most commonly in the southeastern, mid-Atlantic, and central United States.
Blastomycosis: seen in the Missouri and Ohio river valley states (southeastern and south central United States), the Canadian provinces bordering the Great Lakes, and the area adjacent to the St. Lawrence river in New York and Canada.
Aspergillus fumigatus: a ubiquitous soil fungus.
Cryptococcus neoformans: usually an indolent infection found incidentally on immunocompetent patients, cavitation is typically seen in immunocompromised patients.
Actinomycosis, sporotrichosis, mucormycosis, and invasive candidiasis.
Pneumocystis jirovecii (formerly Pneumocystis carinii): seen in HIV patients with CD4 count <200, transplant patients on immunosuppression, or cancer patients undergoing chemotherapy. The rate of cavitation tends to be higher in HIV-positive patients.
Parasites: hydatid cysts, amebic lung abscess, and pulmonary paragonimiasis.
Nocardia: a well-described cause of pulmonary infection, consolidation, and cavitation in those who are immunosuppressed or in those with alveolar proteinosis.
Can lead to cavitation in two ways: central necrosis of the tumor itself or occludes its own blood supply, or postobstructive pneumonitis with abscess formation distal to the neoplasm.
Cavitation detected by CXR is seen in 7–11% of primary bronchogenic carcinomas cavitate.1 Squamous cell carcinoma is the most common variant, cavitating >30% of the time.1,5