Rapidly progressive interstitial lung disease with an organizing pneumonia-dominant high-resolution computed tomography pattern in systemic lupus erythematosus: a case report and literature review.

Among pulmonary involvements of systemic lupus erythematosus (SLE), interstitial lung disease (ILD) is an infrequent but clinically significant complication, with fatal cases reported as "acute lupus pneumonitis" and associated with increased mortality. However, SLE-ILD remains insufficiently stratified according to clinical course, and no predictive factor for rapidly progressive (RP) SLE-ILD, including high-resolution computed tomography (HRCT) pattern, has yet been established. Here we report a 71-year-old man who presented with dyspnea, fever, pancytopenia, anti-double-stranded DNA antibody positivity, hypocomplementemia, proteinuria, and neuropsychiatric symptoms. HRCT initially showed bilateral consolidation predominantly in the peripheral lower lung zones, consistent with organizing pneumonia, followed by rapid extension with ground-glass opacities. He was diagnosed with RP-SLE-ILD with neuropsychiatric involvement and nephritis and improved after intensive combined immunosuppressive therapy. To characterize the HRCT findings of RP-SLE-ILD, we performed a systematic literature review and identified 27 patients with RP-SLE-ILD, including the present case. Organizing pneumonia (OP)-dominant patterns, defined as OP alone or OP combined with nonspecific interstitial pneumonia (OP+NSIP), were significantly more frequent than in the chronic reference cohorts (77.8% vs 10.0% or 14.6%). In contrast, isolated NSIP was significantly less frequent than in the chronic cohorts (3.7% vs 55.0% or 31.5%). These findings suggest that OP-dominant HRCT patterns and lower-lung-zone consolidation may be recurring radiological features among reported RP-SLE-ILD cases, although their predictive value requires validation in consecutive cohorts.