Abstract Introduction Diffuse alveolar hemorrhage (DAH) is a life-threatening clinical syndrome characterized by bleeding in the alveolar spaces originating from the pulmonary microvasculature. The underlying cause is autoimmune in 30-40% of cases. Bleeding is typically multi-lobar and bilateral, though distribution is not a diagnostic criterion. Herein, we describe a case of lung-limited perinuclear anti-neutrophil cytoplasmic antibody-associated (p-ANCA) vasculitis presenting as unilateral alveolar hemorrhage and progressing to alveolar hemorrhage on the contralateral side. Case Description A 35-year-old female with systemic lupus erythematosus presented with small-volume hemoptysis. Initial vital signs showed an oxygen saturation of 96% on ambient air. Computed tomography (CT) of the chest demonstrated extensive ground-glass opacities (GGO) throughout the left lung (Figure 1). Ventilation/perfusion imaging demonstrated a large, matched region of decreased ventilation and perfusion in the left lung. Serial bronchoalveolar lavage (BAL) of the lingula showed high red blood cell (RBC) counts in all samples, the third lavage containing fewer than the second. As the patient was not requiring supplemental oxygen and hemoptysis had resolved, steroids were not administered, and she was discharged on hydroxychloroquine. She presented again eight days later in respiratory distress. She required high-flow nasal cannula with a fraction of inspired oxygen of 50% at 45 liters per minute. Repeat CT demonstrated new GGOs throughout the right lung with near-resolution of the left-sided abnormalities (Figure 1). Serial BAL of the right middle lobe demonstrated high RBC counts, increased from prior. During the second admission, the p-ANCA antibody returned positive at a titer of 1:1280. There was no evidence of antibody-associated vasculitis on renal biopsy. She was treated with methylprednisolone, one gram intravenously daily for three days, and rituximab. With treatment, she was discharged on ambient air with an extended prednisone taper. Discussion While unilateral alveolar hemorrhage is atypical for autoimmune etiologies of DAH, a retrospective study reported up to 44% of DAH cases with unilateral predominance, mainly in the setting of pulmonary congestion due to heart failure. Regarding the migration of alveolar hemorrhage in this case, we hypothesize that hypoxic pulmonary vasoconstriction in the left lung led to increased perfusion to the right, which, combined with active, uncontrolled vasculitis, caused the subsequent right-sided hemorrhage. To the best of our knowledge, this is the first report of unilateral alveolar hemorrhage progressing to contralateral involvement. This case highlights the importance of considering unilateral alveolar hemorrhage and provides a plausible mechanism—hypoxic pulmonary vasoconstriction—to explain unilateral predominance in DAH. This abstract is funded by: None
Blackman et al. (Fri,) studied this question.