Clinical and biological phenotype of patients with KSHV/HHV-8-associated inflammatory cytokine syndrome. (A) Clinical and biological characteristics of 7 patients with KICS; (B-D) phenotype of circulating KIVs detected by standard flow cytometry. (B) Gating strategy used to identify circulating KIVs by selecting IgM⁺CD38⁺ cells among CD3^–CD14^– double-negative population (P1). (C) K and λ light-chain staining among the IgM⁺CD38⁺ population. (D) Percentage of CD19, CD20, CD27, CD40, CD86, and CD24 expression among circulating KIVs (IgM⁺CD38⁺λ⁺) in peripheral blood (n = 5). §, The presence of lymph nodes was assessed by clinical examination and contrast-enhanced computed tomography. “-” means absence of pathological lymphadenopathy, whereas “+” means that pathological lymphadenopathy was present, but the biopsy showed no aspects of MCD. CRP, C-reactive protein; F, female; IgM, immunoglobulin M; M, male; P, patient.