IVLBCL: skin lesions, histology, mutational status, and survival analysis. Skin lesions may present as bluish indurated plaques (A) or generalized telangiectasias (B). Histology of a representative skin biopsy shows a dermal blood vessel with intraluminal clustering of large, blastic cells (HE 1, HE 2), positive for CD20 (clone L26 from Dako, diluted 1:800), CD5 (clone 4C7 from Dako, diluted 1:400), MUM1 (clone MUM1p from Dako, diluted 1:100), IgM (polyclonal, from Dako, diluted 1:500), MYC (clone Y69 from ABCAM, diluted 1:100), and CD10 (clone 56C6 from Dako, diluted 1:20). Original magnification: ×50 for HE 1 and ×400 for HE 2, CD20, CD5, MUM1, IgM, MYC, and CD10. (C) OncoPrinter plot of the targeted next-generation sequencing data shows an MYD88 L265P mutation (NM_001172567) in 44%, a CD79B Y196 mutation (NM_001039933) in 26%, and an EZH2 Y646F mutation (NM_004456) in 4% of the patients. Patient numbers correspond to those in supplemental Table 1. In patients 16 and 2, the sequencing data of CD79B resp. CD79B/A and CARD11 were not reliable because of low read count (<100 reads).