Response to: 'Successful treatment of plasma exchange for refractory systemic juvenile idiopathic arthritis complicated with macrophage activation syndrome and severe lung disease' by Sato et al.

We were very interested to read the correspondence from Dr. Sato and colleagues describing a case of systemic juvenile idiopathic arthritis (sJIA) with associated diffuse lung disease.1 The patient in this new report shares a number of features with cases occurring after exposure to interleukin (IL)-1 or IL-6 inhibitors (n=46) that we recently detailed in an international case series.2 Lung disease complicating sJIA remains a clinical challenge with significant mortality, and we thank the authors for sharing their experience. One of the typical features of this type of lung disease, as illustrated by this case report, is minimal respiratory symptoms despite significant abnormalities on chest CT. The predominant chest CT pattern in our series, as observed in this case, is septal thickening with or without ground-glass opacities, sometimes together with peribronchovascular consolidation. Also like the patient in this report, a majority of cases in our series had refractory sJIA. However, a significant number (~40%) responded to initial treatment, …