Idiopathic Multicentric Castleman Disease (iMCD) is a rare cytokine-driven disorder characterized by systemic inflammation, generalized lymphadenopathy and organ dysfunction. Here, we present an unusual occurrence of iMCD in identical twins and examined the immune milieu within affected lymphoid organs and the host circulation using multi-omic high-dimensional profiling. Using Stereo-seq spatial transcriptomic profiling, we performed unsupervised spatially-constrained clustering to …