PCDLBCL-LT has a distinctive mutational profile which overlaps significantly with that of primary CNS, primary testicular DLBCL, intravascular large B cell lymphoma and the MCD group of DLBCL including a high frequency of MYD88 and CD79B mutations (Table 3) [38, 42–44]. Here, MYD88 is linked to diffuse large B-cell lymphoma.