CD79B is a component of the cell surface B cell receptor complex and is upstream of the NFkB signaling pathway. CD79B mutations at Tyr196 have been reported in approximately 20% of primary testicular diffuse large B cell lymphomas and approximately 10-15% of diffuse large B cell lymphomas overall. CD79B mutations are typically associated with increased cell surface expression of CD79B due to attenuation of the usual negative feedback by LYN kinase. CD79B mutations have been reported to coexist with MYD88 mutations and may be enriched in the activated B cell type of diffuse large B cell lymphoma. The potential for therapeutic targeting of this pathway is currently under investigation.