Differences and similarities of multisystem inflammatory syndrome in children, Kawasaki disease and macrophage activating syndrome due to systemic juvenile idiopathic arthritis: a comparative study

Otar Yener, Gülçin; Paç Kısaarslan, Ayşenur; Ulu, Kadir; Atalay, Erdal; Haşlak, Fatih; Özdel, Semanur; Bozkaya Yücel, Burcu; Gezgin Yıldırım, Deniz; Çakmak, Figen; Öztürk, Kübra; Çakan, Mustafa; Balık, Zeynep; Hasbal Akkuş, Canan; Yıldız, Mehmet; Erat, Tuğba; Çetin, Benhur Şirvan; Yılmaz, Münevver; Bağlan, Esra; Laçinel Gürlevik, Sibel; Atasayan, Vildan; Karadağ, Şerife Gül; Adrovic, Amra; Çağlayan, Şengül; Tanatar, Ayşe; Demirkan, Fatma Gül; Coşkuner, Taner; Akgün, Özlem; Kasap Cüceoğlu, Müşerref; Kavrul Kayaalp, Gülşah; Şahin, Sezgin; Başaran, Özge; Demir, Ferhat; Barut, Kenan; Çiftel, Murat; Gürses, Dolunay; Baykan, Ali; Özsürekçi, Yasemin; Karagöz, Tevfik; Sönmez, Hafize Emine; Bilginer, Yelda; Aktay Ayaz, Nuray; Aydoğ, Özlem; Yüksel, Selçuk; Sözeri, Betül; Kasapçopur, Özgür; Özen, Seza

To compare the clinical and laboratory findings of multisystem inflammatory syndrome in children (MIS-C), patients with Kawasaki disease (KD) and with macrophage activating syndrome due to systemic juvenile idiopathic arthritis (sJIA-MAS) on real-life data. Patients diagnosed with MIS-C, KD, and sJIA-MAS from 12 different centers in Turkey who were followed for at least 6 months were included in the study. Demographic, clinical, and laboratory findings of all patients were analyzed. A total of 154 MIS-C, 59 KD, and 31 sJIA-MAS patients were included. The median age of patients with MIS-C were higher than those with KD while lower than those with sJIA-MAS (8.2, 3, 12 years, respectively). Myalgia (39.6%), cardiac (50.6%), gastrointestinal (72.7%), and neurological (22.1%) involvements were more common in patients with MIS-C compared to others. MIS-C patients had lower levels of lymphocyte (950 vs 1700 cells/µl) and thrombocyte (173,000 vs 355,000 cells/µl) counts and higher pro-BNP (1108 vs 55 pg/ml) levels than KD. Ferritin levels were higher in patients with MIS-C compared to patients with KD while they were lower than patients with sJIA-MAS (440, 170, 10,442 ng/ml, respectively). Patients with MIS-C had a shorter duration of hospitalization than sJIA-MAS (p = 0.02) while they required intensive care unit admission more frequently (55 vs 8 patients, p < 0.001). The median MAS/sJIA score of MIS-C patients was − 1.64 (− 5.23 to 9.68) and the median MAS/sJIA score of sJIA-MAS patients was −2.81 ([− 3.79] to [− 1.27]). MIS-C patients displayed certain differences in clinical and laboratory features when compared to KD and sJIA-MAS. Definition of the differences and similarities between MIS-C and the other intense inflammatory syndromes of childhood such as KD and MAS will help the clinicians while making timely diagnosis.