Classical Hodgkin lymphoma (CHL) is a monoclonal lymphoid neoplasm (in most instances derived from B cells) composed of mononuclear Hodgkin cells and multinucleated Reed-Sternberg (HRS) cells residing in an infiltrate containing a variable mixture of non-neoplastic small lymphocytes, eosinophils, neutrophils, histiocytes, plasma cells, fibroblasts and collagen fibres. Based on the characteristics of the reactive infiltrate and to a certain extent on the morphology of the HRS cells (i.e. lacunar cells), four histological subtypes have been distinguished: lymphocyte-rich classical Hodgkin lymphoma
(LRCHL), nodular sclerosis classical Hodgkin lymphoma
(NSCHL), mixed cellularity classical Hodgkin lymphoma
(MCCHL) and lymphocyte-depleted classical Hodgkin lymphoma
(LDCHL). The immunophenotypic and genetic features of the mononuclear and multinucleated cells are identical in these histological subtypes, whereas their clinical features and association with Epstein-Barr virus (EBV) show differences.