Diffuse large B-cell lymphoma (DLBCL) with significant intravascular invasion. Close resemblance of its clinicopathological features to intravascular large B-cell lymphoma, but not to DLBCL-not otherwise specified

Intravascular Large B-Cell Lymphoma Genomic Profile Is Characterized by Alterations in Genes Regulating NF-κB and Immune Checkpoints

Intravascular large B-cell lymphoma (IVLBCL) is an uncommon lymphoma with an aggressive clinical course characterized by selective growth of tumor cells within the vessels. Its pathogenesis is still uncertain and there is little information on the underlying genomic alterations. In this study, we performed a clinicopathologic and next-generation sequencing analysis of 15 cases of IVLBCL using a custom panel for the detection of alterations in 68 recurrently mutated genes in B-cell lymphomagenesis. Six patients had evidence of hemophagocytic syndrome. Four patients presented concomitantly a solid malignancy. Tumor cells outside the vessels were observed in 7 cases, 2 with an overt diffuse large B-cell cell lymphoma. In 4 samples, tumor cells infiltrated lymphatic vessel in addition to blood capillaries. Programmed death-ligand 1 (PD-L1) was positive in tumor cells in 4 of 11 evaluable samples and in macrophages intermingled with tumor cells in 8. PD-L1 copy number gains were identified in a higher proportion of cases expressing PD-L1 than in negative tumors. The most frequently mutated gene was PIM1 (9/15, 60%), followed by MYD88L265P and CD79B (8/15, 53% each). In 6 cases, MYD88L265P and CD79B mutations were detected concomitantly. We also identified recurrent mutations in IRF4 , TMEM30A , BTG2 , and ETV6 loci (4/15, 27% each) and novel driver mutations in NOTCH2 , CCND3 , and GNA13 , and an IRF4 translocation in 1 case each. The mutational profile was similar in patients with and without evidence of hemophagocytic syndrome and in cases with or without dissemination of tumor cells outside the vessels. Our results confirm the relevance of mutations in B-cell receptor/nuclear factor-κB signaling and immune escape pathways in IVLBCL and identify novel driver alterations. The similar mutational profile in tumors with extravascular dissemination suggests that these cases may also be considered in the spectrum of IVLBCL.

Renal Involvement of CD20-Negative Intravascular Large B Cell Lymphoma with Neurological Manifestations

The involvement of hematological tumors such as lymphoma in the kidneys is a well-recognized phenomenon. Some of the distinct reported pathological processes resulting in kidney dysfunction include minimal change disease, lymphocytic invasion of the parenchyma, immune complex disposition, immunotactoid glomerulopathy, membranous glomerulopathy, and acute tubular injury. We report a rare case of CD20-negative intravascular lymphoma found on a kidney biopsy in a male with primary angiitis of the central nervous system (CNS) who presented with acute kidney injury and proteinuria. After the initiation of rituximab, cyclophosphamide, doxorubicin hydrochloride, vincristine sulfate, and prednisone (R-CHOP), kidney function improved and proteinuria resolved.