Coronavirus disease-2019 (COVID-19) has infected millions of people with high lethality in the world, but little is known whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has impacts on triggering pediatric acute lymphoblastic leukemia (ALL). We present a case of a child with atypical clinical manifestation who developed B-cell acute lymphoblastic leukemia following a mild symptomatic COVID-19 infection. This case underlines the risks of potential oncogenic effects with the history of this viral infection and a state of immunosuppression.

Objective: Double-negative T cells (DNTs) were significantly elevated in autoimmune diseases and were thought to play an important role in inflammation. The purpose of this study was to explore its important role in children with systemic lupus erythematosus (cSLE). Methods: The DNTs, T and B cell subsets of peripheral blood were detected by flow cytometry in 78 patients, and clinical and laboratory data of cSLE patients were collected to analyze the correlation between DNTs and the above indexes. The changes of DNTs after glucocorticoids were detected, and the effects of different doses of glucocorticoids on DNTs were analyzed. Results: DNTs was significantly increased in peripheral blood of cSLE patients. DNTs were associated with SLE disease severity and organ involvement, as well as with the production of autoantibodies, Naive B cell and plasmablast cells. The level of DNTs increased after low-dose glucocorticoid treatment, but the proportion of DNTs gradually decreased with the increase of glucocorticoid dose. Conclusion: DNTs was positively correlated with disease severity in cSLE patients, and the effect of glucocorticoid dose on DNTs was different.