Interstitial Lung Disease: A Rare Association with Adult-Onset Still’s Disease

Pulmonary lung involvement in adult-onset Still’s disease (AOSD) can be classified into two categories: with or without acute respiratory distress syndrome. Interstitial fibrosis in AOSD is rare, occurring in less than 5% of cases. Here, the authors present a case of a 40-year-old male of Asian descent with a past history of hyperthyroidism who presented with fever, shortness of breath associated with cough, sore throat, diffuse arthralgias, pink-coloured rash, and hepatomegaly. Laboratory investigations revealed leukocytosis, abnormal liver function tests, negative antinuclear antibodies, and negative rheumatoid factor. Chest X-ray showed bilateral basal infiltrates, while high-resolution CT chest scan confirmed the diagnosis of interstitial lung disease in association with ASOD. This case suggested a direct association of AOSD and interstitial lung disease, but autoimmune pathogenesis is the only link synchronising both diseases and the exact mechanism of direct involvement is ambiguous.