Pulmonary Tuberculosis (TB): This is often considered the most likely diagnosis for new lung cavitation, especially in the upper lobes, due to its high prevalence worldwide and the typical presentation of cavitation in pulmonary TB.

Lung Abscess: A localized, suppurative infection within the lung parenchyma, often resulting from aspiration of oral or gastrointestinal contents. It can present with cavitation and is more common in certain populations, such as those with altered mental status or dysphagia.
Pneumonia with Cavitation: Certain types of bacterial pneumonia, such as Staphylococcus aureus or Klebsiella pneumoniae, can lead to lung cavitation. This is particularly seen in severe cases or in immunocompromised patients.
Lung Cancer with Cavitation: Although less common, certain types of lung cancer, especially squamous cell carcinoma, can present with cavitation. This diagnosis should be considered, especially in smokers or those with a history of smoking.

Wegener's Granulomatosis (Granulomatosis with Polyangiitis, GPA): An autoimmune disease that can cause lung cavitation among other symptoms. It's crucial to diagnose GPA early due to its potential for severe morbidity and mortality if left untreated.
Septic Emboli: These can occur in the setting of right-sided endocarditis or other sources of bacteremia, leading to lung cavitation. Early diagnosis is critical for appropriate antibiotic treatment and potential surgical intervention.
Invasive Fungal Infections: In immunocompromised patients, fungal infections like Aspergillus can cause lung cavitation. These infections have a high mortality rate if not promptly treated.

Rheumatoid Nodules: In patients with rheumatoid arthritis, lung nodules can occasionally cavitate. This is a rare manifestation but should be considered in the appropriate clinical context.
Eosinophilic Granuloma (Langerhans Cell Histiocytosis): A rare disorder that can cause lung cavitation, typically in smokers. It's part of a spectrum of diseases involving abnormal proliferation of Langerhans cells.
Pulmonary Embolism with Infarction and Cavitation: Although pulmonary embolism typically does not cause cavitation, in rare cases, especially with significant infarction, cavitation can occur. This would be an unusual presentation and should prompt a search for underlying conditions predisposing to thromboembolism.