Besides direct involvement how else may the upper and lower respiratory tracts be affected in Granulomatosis with polyangiitis?
• Bacterial sinusitis, most often due to S. aureus, commonly occurs as a result of obstruction of the paranasal sinus ostia by the inflammatory process and/or chronically damaged nasal passages. Similarly, obstruction of bronchi by nodules or intrabronchial lesions may lead to post obstructive bacterial pneumonia.
• Infections may also result as a complication of treatment-induced immunosuppression. Patients are predisposed to pulmonary infections with opportunistic organisms, such as Pneumocystis jiroveci, herpes viruses, mycobacteria, fungi, and Legionella, as well as the common suppurative bacteria, such as Streptococcus pneumoniae.
• Medications may have direct toxic effects on the lungs. Cyclophosphamide, even in the relatively low doses used to treat GPA, may rarely lead to pulmonary edema or fibrosis. Methotrexate can also be associated with acute pneumotoxicity.
