RESUMEN
Background. Prior research has shown that viruses may trigger JDM, although the degree to which COVID-19 may serve as a trigger for JDM remains unknown. We present two case reports of JDM occurring after COVID-19 infection. We also provide case numbers of new JDM diagnoses pre-and post-COVID-19 as well as an analysis of JDM population characteristics pre-and post-COVID-19. A 5year-old female developed upper respiratory infection (URI) symptoms and was diagnosed with COVID-19 in December of 2020. She developed Gottron's sign, heliotrope rash, and weakness resulting in admission in February of 2021. She had elevated CK, AST, ALT, LDH, and aldolase. Her CMAS (childhood myositis assessment scale) was 24. An MRI showed diffuse myositis. Myositis specific antibody (MSA) testing revealed a positive MJ antibody. She was diagnosed with JDM and started on steroids, methotrexate, hydroxychloroquine, and IVIG with improvement. The second patient was a 4year-old female who was diagnosed with COVID-19 in October 2020. In January 2021, she developed heliotrope rash and Gottron's papules. She developed decreased exercise tolerance in May 2021 found to have elevated Aldolase and LDH. Her CMAS was 34. An MRI showed diffuse myositis. MSA testing was significant for a positive P155/140 antibody. She was started on hydroxychloroquine, steroids, IVIG and methotrexate with improvement. Due to the aforementioned cases a retrospective analysis was performed assessing the characteristics of JDM pre-and post-COVID-19 at Lurie Children's Hospital. Methods. The Cure JM biorepository houses clinical data, laboratory data, and patient samples obtained at the onset of JDM. The following information was obtained from newly diagnosed JDM patients: MSA, DAS (disease activity score), flow cytometry results, vWF antigen, neopterin, CMAS, capillary end row loop(ERL), LDH, Aldolase, ESR, CRP, IgG, complements, ANA, and age at diagnosis. We identified 10 patients with a diagnosis of JDM from January 1st 2020 -July 1st 2021 who were designated as the post-COVID-19 group. This population was compared to a total of 51 patients diagnosed with JDM between Jan 1st 2010 and December 31st 2019 who were designated as the pre-COVID-19 group. Data analysis was performed using Welch T-testing. Research enrollment was impacted due to the COVID-19 pandemic. To better assess JDM rates, chart review and EMR reports were obtained to determine the total number of JDM diagnoses. Results. T-testing showed no significant change in DAS, ERL count, T or B cell flow cytometry, vWF antigen, CK, CMAS, CRP, Aldolase, LDH, IgG, complements or ANA titer between the pre-and post-COVID-19 JDM groups. The analysis showed a significant change in NK cell population with a decrease in the absolute NK cell number (pre 163, post 90.75. P value 0.03), and NK cell percentage (pre 6.6%, post 3.625%, P value 0.008). Both of the patients presented in this case report showed a low NK cell number (1% and 3% respectively). The total number of new JDM cases rose from an average of 6.3 cases per year to an average 9 cases per year from January 1st 2020 to December 31st 2021. Conclusion. This study provides two case reports of COVID-19 likely triggering JDM. This study also shows a modest increase in the number of new JDM cases since the onset of the pandemic. Interestingly, the NK cell population in the post-COVID-19 JDM patients were significantly decreased. NK cells have multiple roles in not only immune regulation, but also the immune response to viruses. This study suggests that NK cells play a role in the development of in virally mediated JDM, specifically in cases triggered by COVID-19. Future studies will be important to further delineate the function of NK cells in these patients. Markers of JDM disease severity, including DAS, Neopterin, CK, and CMAS, did not significantly change in our institution's JDM population after the onset of the COVID-19 pandemic.