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

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 the exclusion of other life-threatening diseases has major caveats. In the era of this pandemic, diagnosis of other life-threatening diseases might delay treatment. The Food and Drug Administration has recently authorized the first antibodybased test for COVID-19; however, RT-PCR of nasopharyngeal or oropharyngeal swabs remains the recommended test for diagnosis. We present the first report of a false positive COVID-19 antibody test in a case of Granulomatosis with Polyangiitis (GPA). Specifically, the case concerns an 82-year-old female, never smoker, who was admitted to our hospital with symptoms of fever and general fatigue that had lasted 7 days. She already had a positive IgM test for COVID-19, yet multiple RT-PCR tests had returned as negative for SARS-CoV-2. In the following days, her 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 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 patient evaluation in order to avoid misdiagnosis in the era of COVID-19.

COVID-19-induced granulomatosis with polyangiitis

“…8 Another case report described a patient diagnosed with GPA with positive COVID-19 IgM and negative PCR test. 9 However, in our case, GPA developed 4 weeks after true COVID-19 infection confirmed by positive SARS-CoV-2 PCR test. Treatment of GPA involves a multidisciplinary approach and usually includes corticosteroids, rituximab or cyclophosphamide.…”

Patient with Antineutrophil Cytoplasmic Antibody Associated Small Vessel Vasculitis, Acute Renal Failure, and Coronavirus Disease-19 Pneumonia: A Diagnostic and Therapeutic Challenge

“…Later on in the hospitalization, nasal RT-PCR SARS-COV 2 test was positive, and COVID-19 pneumonia soon emerged. We found only one report of false-positive SARS COV 2 RT-PCR test in a patient with AAV, potentially due to cross-reactivity [22]. This was not the case with our patient because a positive RT PCR test was confirmed twice and the disease progressed with worsening of the clinical and radiological features.…”

New Onset Granulomatosis with Polyangiitis Associated with COVID-19

“…Furthermore, a review of 8,136 pooled specimens showed RT-PCR positivity using nasopharyngeal swabs to be a mere 45.5% (compared to bronchoalveolar lavage with 91.8%) [ 6 ]. Our patient showed positive IgM antibodies to COVID-19, owing to possible recent infection, although there has been a report of cross-reactivity to COVID-19 IgM serological testing in GPA [ 7 ]. We are hesitant to conclude this case as a false-positive, rather we hypothesize patient's delayed presentation and low-yield specimen for PCR testing may have missed an active or recent COVID-19 infection (as illustrated in Figure 1 ).…”