Single cell landscape of Multicentric Castleman Disease in monozygotic twins

Idiopathic Multicentric Castleman Disease (iMCD) is a rare IL-6-driven hematological disorder characterized by systemic lymphadenopathy, elevated immunoglobulin levels, and prominent plasmacytosis in the bone marrow and lymph nodes. Here, we present an unusual occurrence of iMCD in identical twins. Using single cell sequencing, we identified nodal endothelial cells and fibroblastic reticular cells as the source of IL-6 signals. An “inflammatory†peripheral monocytosis enriched for the expression of S100A family genes was evident in both twins, as well as a group of monocytes expressing cytotoxic gene signatures in the affected twin with milder clinical manifestations.EGA study EGAS00001007390