AUTHOR=Tzouvelekis Argyrios , Karampitsakos Theodoros , Krompa Anastasia , Markozannes Evangelos , Bouros Demosthenes 

TITLE=False Positive COVID-19 Antibody Test in a Case of Granulomatosis With Polyangiitis

JOURNAL=Frontiers in Medicine

VOLUME=Volume 7 - 2020

YEAR=2020

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2020.00399

DOI=10.3389/fmed.2020.00399

ISSN=2296-858X

ABSTRACT=Collateral damage due to 2019 novel coronavirus disease (COVID-19) represents an emerging issue. Symptoms of COVID-19 are not disease-specific. Differential diagnosis is challenging and exclusion of other life-threatening diseases has major caveats. In the era of this pandemic, diagnosis of other life threatening diseases might delay. Food and Drug Administration has recently authorized the first antibody-based test for COVID-19; yet, RT-PCR of nasopharyngeal or oropharyngeal swab is the recommended test for diagnosis. We present the first report of false positive COVID-19 antibody test in a case of Granulomatosis with Polyangiitis (GPA). In particular, an 82-year-old female, never smoker, was admitted to our hospital with symptoms of fever and general fatigue the past 7 days. She already had a positive IgM test for COVID-19, yet multiple RT-PCR tests negative for SARS-CoV-2. The following days renal function deteriorated, while hematuria and proteinuria with active urinary sediment developed. Based on high clinical suspicion for ANCA-associated vasculitis we performed a complete immunologic profile which revealed positive c-ANCA with elevated titers of anti-PR3. Pulses of methylprednisolone for three days along with cyclophosphamide were applied. At day 10, treatment response was noticed as indicated by respiratory and renal function improvement. This report highlights the need for meticulous patients’ evaluation in order to avoid misdiagnosis in the era of COVID-19.