Lung cavities. Coloured chest X-ray showing large cavities (dark red) in the lungs of a patient in a case of Wegener's granulomatosis. This is a rare vascular disorder where blood vessel inflammation (vasculitis) causes the formation of granuloma (inflammatory lesions). These lesions can form in the lungs, kidneys and nasal passages. The lesions can either help in repairing the tissue or cause further damage, leading to widespread tissue death (necrosis). The large cavities seen here are due to necrosis of lung tissue. Treatment is with high doses of steroids initially, and low doses for one year. If diagnosed early, most patients recover.