There have been a limited number of studies on coronavirus disease 2019 (COVID‐19) in children. In this study, we aimed to investigate the demographic, clinical, and laboratory features of COVID‐19 and to identify the role of mean platelet volume (MPV) in predicting the prognosis in children. A single‐center retrospective study, including 251 confirmed and 65 suspected COVID‐19 cases, was conducted between March 11, 2020, and December 11, 2020. In the confirmed COVID‐19 group, 48 (19.1%) patients were asymptomatic, 183 (72.9%) mild, 16 (6.4%) moderate, 1 (0.4%) severe, and 3 were (1.2%) critically ill. Confirmed COVID‐19 patients had significantly lower mean values of white blood cell (WBC), absolute neutrophil count, absolute lymphocyte count, platelet, and hemoglobin (p < .001). However, there was no significant difference in MPV levels between the two groups (p = .894). C‐reactive protein (CRP), procalcitonin, fibrinogen, and NT‐pro‐BNP mean values were significantly lower in confirmed COVID‐19 cases than suspected cases (p < .001). A total of 55 (21.9%) patients required hospitalization due to COVID‐19, and MPV, WBC, CRP, procalcitonin, D‐dimer, and NT‐pro‐BNP were statistically higher in hospitalized patients than those in outpatients. The multivariate analysis of confirmed COVID‐19 cases according to the severity of disease showed that lymphopenia and higher levels of fibrinogen significantly associated with severe clinical symptoms. Decision tree analysis showed that the most powerful predictor of hospitalization due to COVID‐19 was the D‐dimer (p < .001). MPV values are not associated with COVID‐19 disease severity. However, MPV can be used with other parameters such as WBC, CRP, procalcitonin, D‐dimer, and NT‐pro‐BNP to predict hospitalization.

Multisystem Inflammatory Syndrome (MIS-C) is a new entity that emerges 2–4 weeks after the SARS-CoV-2 infection in children. MIS-C can affect all systems, the most severe of which is cardiac involvement. The duration of the cardiac symptoms is still uncertain and may be persistent or prolonged. The American College of Rheumatology Clinical Guidelines recommends cardiac magnetic resonance imaging (MRI) 2–6 months after the diagnosis of MIS-C in patients presenting with significant transient left ventricular (LV) dysfunction in the acute phase of illness (LV ejection fraction 50%) or persistent LV dysfunction. There are a few studies investigating cardiac MRI findings in MIS-C patients. In this study, we aimed to evaluate cardiac MRI findings, at the earliest 3 months after diagnosis, and compare these findings with the echocardiograms in children with MIS-C. A retrospective study including 34 MIS-C patients was conducted at a tertiary-level University Hospital between June 2020 and July 2021. Centers for Disease Control and Prevention criteria were used in the diagnosis of MIS-C. Cardiac MRI was performed at least 3 months after MIS-C diagnosis. The study included 17 (50%) boys and 17 (50%) girls with a mean age of 9.31 ± 4.72 years. Initial echocardiographic evaluation revealed cardiac abnormality in 13 (38.2) patients; 4 (11.8%) pericardial effusion, 4 (11.8%) left ventricular ejection fraction (LVEF) < 55%, and 5 (14.7%) coronary artery dilatation. Echocardiography showed normal LV systolic function in all patients during follow-up; coronary dilatation persisted in 2 of 5 (40%) patients at the 6th-month visit. Cardiac MRI was performed in 31 (91.2%) patients, and myocardial hyperemia was not detected in any patients (T1 relaxation time was < 1044 ms in all children). However, 9 (29%) patients’ MRI showed isolated elevated T2 levels, and 19 (61.3%) revealed at least one of the following findings: pericardial effusion, right ventricular dysfunction, or LVEF abnormality. In patients with MIS-C, a high rate of cardiac involvement, particularly pericardial effusion was determined by cardiac MRI performed at the earliest 2–6 months after diagnosis. Even if echocardiography does not reveal any abnormality in the initial phase, cardiac MRI should be suggested in MIS-C patients in the late period. This is the first study reporting cardiac MRI findings in the late period of MIS-C patients.

Bone and joint infections are common in children, particularly those under 10 years of age. While antimicrobial therapy can often successfully treat these infections, surgical drainage may also be necessary. It is important to note that prolonged courses of treatment have been associated with adverse events and drug reactions. Among these, drug reactions with eosinophilia and systemic symptoms (DRESS) syndrome is particularly severe and potentially life-threatening. We aimed to evaluate the cases of DRESS syndrome that develop during the treatment of bone and joint infections. A retrospective study was conducted at a tertiary-level university hospital between 2015 and 2022 to determine the incidence and outcomes of definite DRESS Syndrome in children under 18 years of age with bone and joint infections. Of 73 patients with bone and joint infections, 16 (21.9 %) children developed antimicrobial therapy-induced DRESS syndrome. Eight (50 %) of these children were boys; the mean age of the patients was 9.76 ± 5.5 years. DRESS syndrome occurred in 16 children, including 13 children with osteomyelitis, 1 child with osteomyelitis and septic arthritis, and 2 children with septic arthritis and sacroiliitis. The mean duration of intravenous antibiotic therapy was 40.6 ± 16.6 days; the mean hospital stay was 48.7 ± 23.7 days; the mean time for the development of DRESS syndrome after starting antibiotics was 19.6 ± 7.68 days. New onset fever (68.8 %) and rash (43.8 %) were the most common symptoms of DRESS Syndrome. Cefotaxime and vancomycin were drugs responsible for DRESS syndrome in 8 (50 %) of 16. The causative antibiotics were switched to another class of antibiotic, most commonly preferred was ciprofloxacin (n:5; 31.3 %). For children with persistent symptoms, steroids were used in 5 (31.25) patients. Clinicians should be aware of DRESS syndrome in children who develop fever and rash under long-term antibiotics and should check hematological and biochemical parameters to predict the severity of DRESS syndrome. In patients with persistent symptoms, steroids may be used to control the symptoms.