Describing and expanding the clinical phenotype of anti-MDA5-associated rapidly progressive interstitial lung disease: case series of nine Canadian patients and literature review

Objective: To describe and expand the phenotype of anti-MDA5-associated rapidly progressive interstitial lung disease (MDA5-RPILD) in Canadian patients.Method: All proven cases of MDA5-RPILD hospitalized in the University of Montreal’s affiliated centres from 2004 to 2015 were selected for inclusion.Results: Of nine consecutive patients, RPILD was the presenting manifestation in seven, whereas two patients developed RPILD 2 years after the onset of arthritis and of chronic interstitial lung disease. In the case with arthritis, RPILD was probably triggered by initiation of tumour necrosis factor-α-inhibitor therapy. In most patients (89%), RPILD was accompanied by concomitant onset of palmar/lateral finger papules, skin ulcerations, and/or mechanic’s hands. All patients experienced profound weight loss over 1–2 months (mean ± SD 10.2 ± 4.8 kg). All had arthralgias and/or arthritis. Six patients were clinically amyopathic; only one patient had creatine kinase (CK) levels > 500 U/L. Initial ferritin and tran...