Rheumatoid Arthritis (RA) with Pulmonary Involvement: This is a common condition that can cause swelling of the metacarpophalangeal (MCP) joints and also lead to lung lesions, including cavitary lesions, due to rheumatoid nodules or other pulmonary manifestations of RA.

Granulomatosis with Polyangiitis (GPA): Formerly known as Wegener's granulomatosis, GPA is a form of vasculitis that can cause both joint swelling and cavitary lung lesions due to granulomatous inflammation.
Infectious Endocarditis: Although more commonly associated with heart valve issues, infectious endocarditis can lead to systemic emboli, including septic emboli to the lungs, which might appear as cavitary lesions, and also cause joint swelling due to immune complex deposition.
Sarcoidosis: This condition can cause joint swelling and pulmonary lesions, including cavitary lesions, although the latter is less common. Sarcoidosis leads to granulomatous inflammation in various organs.

Tuberculosis (TB): TB can cause both joint swelling (septic arthritis) and cavitary lung lesions. It's crucial to consider TB, especially in endemic areas or in individuals with risk factors, as it requires specific antimicrobial treatment.
Lung Cancer with Metastasis: Although less likely, lung cancer can cause cavitary lesions, and if it metastasizes to the bone or causes paraneoplastic syndromes, it could lead to joint swelling.
Endocarditis due to Staphylococcus aureus: This condition can lead to septic emboli causing cavitary lung lesions and also cause joint infections or swelling.

Relapsing Polychondritis: A rare autoimmune disorder that can cause inflammation of cartilaginous structures, including joints, and also lead to respiratory symptoms, although cavitary lung lesions would be an uncommon manifestation.
Ehlers-Danlos Syndrome with Pulmonary Involvement: Some types of Ehlers-Danlos syndrome can lead to pulmonary complications, including spontaneous pneumothorax or, rarely, cavitary lesions, and also cause joint hypermobility or swelling.
Pulmonary Langerhans Cell Histiocytosis: A rare condition that can cause cavitary lung lesions and, in some cases, might be associated with systemic symptoms, including joint involvement, although this would be uncommon.