We describe the case of a previously healthy male patient who presented to a respiratory clinic with sinusitis, pulmonary cavities, and hemoptysis. Three weeks following a diagnosis of Granulomatosis with Polyangiitis (GPA) and initiation of immunosuppressive treatment, the patient suddenly developed a large pneumothorax that was complicated by empyema. In this report we discuss and highlight the rare pleural complications associated with GPA, and alert clinicians to monitor for these important complications even after disease-modifying treatment is initiated.