SFTPD and macrophage activation syndrome: The reasons for the differences between these studies and the present one could be related to multiple factors: a younger study population (mean age 49 years for Kerget and Tong's studies; mean age 59 years for our population); ethnical differences (Turkish and Chinese population, respectively); different treatments received during in-hospital stay: some patients from Kerget et al. were treated for suspected MAS with tocilizumab (an anti-IL-6 treatment), with a concomitant decrease in SP-D levels, which was not the case in our cohort.