Cavitating Nodules:
Etymology:
Derived from the Latin word cavus, meaning “hollow,” referring to the central cavity within the nodule.
AKA:
- Cavitary nodules
- Cavitated pulmonary nodules
What is it?
Cavitating nodules refer to pulmonary nodules that contain necrosis or gas-filled spaces within a surrounding wall of lung parenchyma. These are visible on imaging and can indicate various infectious, neoplastic, or inflammatory processes.
Caused by:
- Infectious:
- Bacterial (e.g., Staphylococcus aureus, Klebsiella pneumoniae)
- Fungal (e.g., aspergillosis, histoplasmosis)
- Tuberculosis (reactivation TB)
- Septic emboli (multiple cavitating nodules)
- Neoplasm:
- Primary lung cancer (e.g., squamous cell carcinoma, adenocarcinoma)
- Metastatic cancer (e.g., squamous cell metastases, sarcomas)
- Inflammatory/Immune:
- Granulomatosis with polyangiitis (GPA)
- Rheumatoid nodules (associated with rheumatoid arthritis)
- Circulatory:
- Pulmonary infarction with secondary infection or necrosis
- Septic emboli (e.g., in IV drug users)
- Inhalational Exposure:
- Pneumoconiosis (e.g., silicosis with secondary TB or necrosis)
- Iatrogenic:
- Post-radiotherapy changes
- Trauma:
- Pulmonary contusion or hematoma (may cavitate if infected)
- Congenital/Inherited:
- Bronchogenic cysts (cavitating after infection)
- Metabolic/Infiltrative:
- Pulmonary amyloidosis (rarely cavitating in nodular form)
Resulting in:
- Central gas-filled spaces within a nodule
- Variably thick walls depending on the cause
- Potentially multiple nodules with a cavitating appearance
Structural Changes:
- Lung parenchymal necrosis
- Gas or fluid-filled cavities within nodular lesions
- Disruption of alveolar architecture
Pathophysiology:
- Necrosis or gas formation within a lung nodule
- Infectious or neoplastic processes leading to destruction of lung tissue
- Thick-walled cavities suggest malignancy or aggressive infections
Pathology:
- Infectious: Necrotizing pneumonia with polymorphonuclear infiltration
- Neoplastic: Tumor necrosis with central cavitation
- Inflammatory: Granuloma formation with central necrosis
Diagnosis:
- Clinical correlation with risk factors (e.g., smoking, IV drug use, immune status)
- Imaging with CXR and CT (wall thickness and cavity size critical for differentiation)
- Biopsy or microbiological analysis for definitive diagnosis
Clinical:
- Symptoms may include cough, hemoptysis, fever, or chest pain
- Asymptomatic cases can be detected incidentally on imaging
Radiology:
- CXR:
- Findings: Round or oval nodules with central lucency surrounded by a dense wall
- Associated Findings: Variable wall thickness
- CT:
- Parts: Nodule with a central cavity
- Size: Typically >10 mm but can vary
- Shape: Round or oval, wedge-shaped with a feeding vessel sign in septic emboli
- Position: Solitary or multiple, randomly distributed or localized (e.g., upper lobes in TB); septic emboli often demonstrate a bilateral peripheral distribution with lower lobe predominance.
- Character: Wall thickness >15 mm suggests malignancy, while thin walls (<4 mm) suggest benign causes like abscesses
- PET-CT:
- Useful to distinguish malignant nodules from benign causes based on metabolic activity, though active infection can also be PET avid, limiting specificity.
Other Imaging Modalities:
- MRI: Limited use but can help in soft tissue characterization
- Ultrasound: May be useful for percutaneous biopsy guidance
Pulmonary Function Tests (PFTs):
- Typically normal unless cavitation involves significant lung parenchyma
Management:
- Imaging Evaluation:
- CT chest with contrast to assess wall thickness, size, and distribution
- PET-CT for metabolic activity if malignancy is suspected
- Microbiological Workup:
- Sputum and blood cultures for suspected infections
- Histopathological Analysis:
- Biopsy or surgical resection if malignancy is suspected
Recommendations:
- Assess clinical history and risk factors (e.g., IV drug use, smoking, immune suppression)
- Perform contrast-enhanced CT for detailed imaging
- Initiate appropriate antimicrobial therapy for infectious causes
- Consider biopsy for persistent or suspicious nodules
Key Points and Pearls:
- Wall Thickness: Thick walls (>15 mm) suggest malignancy, while thin walls (<4 mm) suggest benignity.
Thick-walled cavities (>15 mm) are often seen in malignant processes such as squamous cell carcinoma. Radiopaedia
- Septic Emboli: Consider in IV drug users with multiple cavitating nodules, often with a wedge shape and feeding vessel sign.
Septic emboli typically present as multiple cavitating nodules with a peripheral distribution and a feeding vessel sign, common in intravenous drug users. Radiographics
- Upper Lobe Predominance: Common in TB or post-primary infections.
Post-primary tuberculosis often involves the upper lobes with cavitating lesions. Radiopaedia
- Timely Recognition: Critical for appropriate management and early intervention.
Early identification of cavitary nodules can guide effective treatment, particularly in distinguishing between infectious and malignant etiologies. RadiologyKey