Characteristics of Systemic Lupus Erythematosus Patients with Diffuse Alveolar Hemorrhage: Clinical Features and Outcomes from a Single-Center Experience

<b>Background/Objectives</b>: Diffuse alveolar hemorrhage (DAH) is a rare but life-threatening complication that might occur in the course of systemic lupus erythematosus (SLE), presenting with acute respiratory symptoms, a rapid drop in hemoglobin, and diffuse pulmonary infiltrates. Despite various studies, clinical and laboratory risk factors for DAH in SLE remain unclear due to small cohort sizes and inconsistent findings. <b>Methods</b>: We analyzed the medical records of all adult SLE patients treated at the University Hospital in Kraków, Poland, from 2012 to 2022, to look for patients with DAH. <b>Results</b>: In a cohort of 1039 SLE patients, DAH was confirmed in five cases (0.48%), all presenting with respiratory symptoms and significant hemoglobin drops. No patients required intensive care unit admission or mechanical ventilation, and all survived the 5-year follow-up after receiving immunosuppressive therapy including glucocorticosteroids and cyclophosphamide, and also rituximab in one case. Common features included constitutional symptoms, hematologic and renal involvement, and frequent presence of antiphospholipid antibodies, with antiphospholipid syndrome diagnosed in three patients (60%). All patients had positive antinuclear antibodies, with the presence of anti-dsDNA and anti-SSA antibodies, each present in 3 out of 5 cases. <b>Conclusions</b>: In conclusion, early recognition and aggressive treatment of DAH in SLE patients, who often present other medical comorbidities as hematological, renal, and cardiovascular manifestations, is critical for improving long-term outcomes.