Even if it looks like COVID-19, think again: the importance of differential diagnosis during a pandemic.

Introduction: Antisynthetase syndrome (ASSD) is a rare auto-immune condition that can present as interstitial lung disease (ILD) and progress into Acute Respiratory Distress Syndrome (ARDS).

Importance: The purpose of this clinical case is to highlight the importance of considering less prevalent causes of ARDS amid the COVID-19 pandemic.

Case Report: We present a 56-year-old Belgian female of African descent without past medical history who demonstrated typical signs of COVID-19 at the start of the pandemic. Based on the disease course as well as CT-scan findings, a diagnosis of COVID-19 was made. She progressed to ARDS for which she got intubated and was started on venovenous membrane oxygenation (VV-ECMO). Despite initial negative screening for antinuclear antibodies, further analysis revealed anti-Jo-antibodies. Diagnosis of ASSD was eventually retained and immunosuppressive therapy was started. However, pulmonary fibrosis had evolved too far and therapy was halted shortly after.