The balance between autoimmunity and infection: a case report of concomitant pathology of pulmonary nocardia and granulomatosis with polyangiitis at initial presentation

Pulmonary nocardiosis may clinically and radiologically mimic granulomatosis with polyangiitis, and both conditions can rarely present simultaneously.Histopathological examination is crucial to distinguish infectious mimics from vasculitis in anti-neutrophil cytoplasmic antibodies-positive patients.A stepwise treatment strategy in which controlling infection before initiating immunosuppression can reduce the risk of complications in dual pathology.