CyTOF panel for the simultaneous assessment of HRS cells and infiltrating immune cells. The CyTOF panel identifies cells of T, B, NK, and macrophage lineages. CD4⁺ and CD8⁺ T cells can be further discriminated based on differentiation, polarization, and functional status. Malignant HRS cells are defined by their expression of CD30⁺ and CD15⁺, in addition to PAX5, PD-L1, PD-L2, and pSTAT1.