Fig. 1: A representative case of plasmablastic lymphoma.

Dense sheets of blast-like cells with elevated proliferative activity (HE, ×400; a; MiB1, ×400; e) and prominent plasmablastic/partially immunoblastic morphology (Giemsa, ×400; b). Immunophenotypically, the malignant cells are predominantly negative for most B-cell antigens like CD20 (×400, d), while several post-germinal and/or plasmacytic antigens (e.g., CD38) are strongly expressed (×400, c). As a potential therapeutic target as well as a novel means of prognostication, CD30 is expressed in a significant subset of PBL patients (CD30 ×400; ~15% positivity in the present case). By means of Fluorescence in situ hybridization for MYC, patients were subdivided into cases with wild-type MYC, MYC amplification (g) and MYC split ( ± concurrent amplification; h; in this case without concurrent amplification). Overview of clinical outcome according to cytogenetic MYC categories (i and l; wild-type (wt), split ( ± amp), amplification (amp) or any type of alteration (alt)) suggests a similar clinical course for patients harboring MYC amplifications when compared to MYC wild-type patients. Overall (m and n) and progression-free survival (j and k) according to MYC status (split vs. wt+amplification; OS: p = 0.0318; HR: 2.071; CI: 1.082–3.967; PFS: p = 0.0884; HR: 1.667; CI: 0.8902–3.120) and immunohistochemical expression of CD30 (OS: p = 0.0155; HR: 0.5185; CI: 0.2885–0.9321; PFS: p = 0.0617; HR: 0.6364; CI: 0.360–7.030) reveal significantly divergent clinical outcome (Gehan–Breslow–Wilcoxon test).