When idiopathic multicentric Castleman disease meets COVID-19: a multicenter retrospective study from China.

Idiopathic multicentric Castleman disease (iMCD) is a rare and cytokine storm-driven inflammatory disorder. The exact cause of iMCD is still unknown, although several hypotheses have been proposed. However, regardless of the underlying cause, the ultimate result is the activation of the inflammatory pathway, which can lead to damage in multiple organs. Currently, there have been several reports highlighting the intricate link between coronavirus disease 2019 (COVID-19) and iMCD. To better understand the impact of COVID-19-induced immune storm on iMCD, we conducted a multicenter retrospective study in three hospitals in China. A total of 28 patients with iMCD were included, among whom 25 had confirmed COVID-19 infection, and we presented 4 cases that showed different disease progression after the infection of COVID-19, including 2 who did not receive any treatment for Castleman disease before. Our findings underscore the necessity of carefully monitoring iMCD patients with COVID-19 and promptly intervening to address any changes in their condition. Besides, this study also summarized the shared cytokines between COVID-19 and iMCD. Recent studies have shown promising results in treating severe COVID-19 and iMCD using tocilizumab, an interleukin-6 receptor antagonist. Therefore, it suggests that other potential cytokine storm therapy targets that have been effective in COVID-19 may also be explored for the treatment of iMCD.