A Rare Case of Rapidly Progressive Diffuse Parenchymal Lung Disease

We present a case of a 56-year-old man with progressive dyspnoea and dry cough for over one month, initially treated as community-acquired pneumonia without improvement. Despite antibiotics and steroids, his respiratory function worsened, accompanied by haemoptysis and escalating oxygen needs, necessitating intubation. Laboratory evaluation revealed elevated C-reactive protein (CRP), negative infectious disease panel, a positive myositis panel (anti-PL-12), and SSA/Ro52 antibodies. Chest computed tomography (CT) showed extensive subpleural ground-glass opacities consistent with rapidly progressive interstitial lung disease (ILD). Given the diagnosis of anti-synthetase syndrome (ASS), high-dose pulse methylprednisolone (500 mg intravenous [IV] for 3 days) and rituximab (1 g IV, two doses) were instituted. The patient exhibited marked clinical and radiologic improvement, achieving extubation on Day 10. Post-therapy imaging demonstrated near resolution of ground-glass opacities, leaving reticulations indicative of chronic fibrosis. This case underscores the significance of early recognition and aggressive immunomodulation in ASSassociated ILD. High-dose steroids and rituximab may offer critical benefits in refractory, rapidly progressive lung involvement. A multidisciplinary approach remains essential, and further research is needed to establish standardised treatment protocols.