Abstract Background Granulomatosis with polyangiitis (GPA) is a rare ANCA-associated vasculitis with a prevalence of 1–2 cases per 100,000 person-years. While classically involving the upper airways, lungs, and kidneys, GPA can occasionally present as isolated pulmonary disease. Such presentations often mimic infectious or organizing pneumonias, leading to delayed diagnosis and treatment. This case highlights the importance of considering vasculitis in patients with subacute, treatment-resistant pneumonia, an essential diagnostic awareness for clinicians. Case Report A 29-year-old previously healthy male presented with three weeks of progressive dyspnea, cough, and fever. He was diagnosed with community-acquired pneumonia and treated sequentially with amoxicillin/clavulanate, azithromycin, and levofloxacin without improvement. Imaging revealed bilateral nodular consolidations with extensive ground-glass opacities on CT. Despite broad-spectrum antibiotics (vancomycin and cefepime), he developed worsening hypoxemia requiring high-flow nasal cannula and ICU admission. Infectious workup was negative, including bacterial, fungal, and viral studies. Laboratory evaluation showed elevated inflammatory markers, rheumatoid factor of 142 IU/mL, anti-CCP 7 units, and positive c-ANCA (1:160) with anti–PR3 antibodies. Bronchoalveolar lavage plus transbronchial biopsies demonstrated hemosiderin-laden macrophages consistent with diffuse alveolar hemorrhage. Intravenous methylprednisolone (250 mg daily) was initiated for suspected vasculitis, later escalated to pulse dose steroids after laboratory studies resulted due to worsening oxygenation and symptomatology. Rituximab and avacopan were subsequently added for induction therapy. The patient’s respiratory status improved, and he was successfully weaned from oxygen and transitioned to oral prednisone. Notably, there was no renal or upper airway involvement throughout his course. Discussion and Conclusion This case illustrates pulmonary-limited GPA masquerading as subacute pneumonia unresponsive to antibiotics. In patients with pneumonia with persistent hypoxemia despite appropriate antimicrobial therapy, other causes of hypoxemia such as vasculitis, including GPA should remain on the differential even in the absence of extrapulmonary manifestations. Early recognition and timely immunosuppressive therapy are critical to preventing irreversible lung injury and improving patient outcomes. This abstract is funded by: None
Gronewold et al. (Fri,) studied this question.