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Signature ✍️
- A cavitary lung lesion represents a region of lung parenchymal necrosis that has been cleared out via bronchial drainage of the necrotic lesion’s center, thereby leaving a “hollowed out” space (”cavity”)
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DDx 🏳️🌈
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- Acute (Necrotizing) 💀
- Focal
- Staph. aureus & Strep. pyogenes
- Klebsiella & Pseudomonas spp.
- Metastatic
- Infective Endocarditis
- Separate DDx
- Endovascular Infection
- Strep. mitis group (e.g. intermedius, constellatus)
- Fusobacterium spp. (e.g. necrophorum)
- Subacute-Chronic (Granulomatous) 💀
- Mycobacterial
- Tuberculosis (upper-lobe predominant)
- Non-tuberculous mycobacteria (lower-lobe predominant)
- Fungal
- Endemic mycoses (e.g. histoplasmosis)
- Molds (i.e. aspergillosis, mucormycosis)
- Cryptococcosis
- Parasitic
- Paragonimiasis
- Echinoccocosis
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- Solid
- Squamous cell carcinoma (primary ⊕ secondary)
- Lymphoproliferative
- Lymphomatoid granulomatosis
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- Granulomatosis with polyangiitis (GPA)
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- Pulmonary infarction
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Principles❗️
Mechanisms of Disease 💀
- Suppurative necrosis (i.e. pyogenic infection)
- Caseous necrosis (e.g. tuberculosis)
- Ischemic necrosis (e.g. pulmonary infarction, GPA, lymphoma)
- Internal desquamation of tumor ⊕ subsequent liquefaction (i.e. solid malignancy)
Cavity Wall Thickness 🤏
- The measurement of thickest cavity wall is the most useful tool in predicting malignant vs. non-malignant cavitary lesions:
- Cavities w/ a max wall thickness of < 4mm non-malignant 94% of the time
- Cavities w/ a max wall thickness of > 15mm malignant 90% of the time
- Cavities w/ a max wall thickness of 5-15mm are mixed malignant & non-malignant
⚪ Note: this rule of thumb is far from perfect, however. Some cases of non-malignant diseases such as chronic GPA are well-described to cause very thick cavitary lesions
Location, Location, Location ⊕ Infection❓
- If the largest cavitary lesion is inside an upper lobe, tuberculosis is more likely
- If cavitary lung lesions are smaller & located at the bases, this may suggest non-tuberculous mycobacteria (e.g. chronic aspiration, esophageal dysmotility)
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