Intravascular large-B-cell lymphoma (IVLBCL) is a unique type of extranodal lymphoma characterized by selective growth of tumor cells in small vessels without lymphadenopathy. Greater understanding of the molecular pathogenesis of IVLBCL is hampered by the paucity of lymphoma cells in biopsy specimens, creating a limitation in obtaining sufficient tumor materials. To uncover the genetic landscape of IVLBCL, we performed whole-exome sequencing (WES) of 21 patients with IVLBCL using plasma-derived cell-free DNA (cfDNA) (n = 18), patient-derived xenograft tumors (n = 4), and tumor DNA from bone marrow (BM) mononuclear cells (n = 3). The concentration of cfDNA in IVLBCL was significantly higher than that in diffuse large-B-cell lymphoma (DLBCL) (P < 0.0001) and healthy donors (P = 0.0053), allowing us to perform WES, and most mutations detected in BM tumor DNA were successfully captured in cfDNA and xenograft. IVLBCL showed a high frequency of genetic lesions characteristic of activated-B-cell-type DLBCL; with the former showing conspicuously higher frequencies (compared to nodal DLBCL) of mutations in MYD88 (57%), CD79B (67%), SETD1B (57%), and HLA-B (57%). We also found that 8 (38%) IVLBCL harbored rearrangements of PD-L1/PD-L2 involving the 3′-UTR; such rearrangements are implicated in immune evasion via PD-L1/PD-L2 overexpression. Our data demonstrate the utility of cfDNA and imply important roles for immune evasion in IVLBCL pathogenesis and PD-1/PD-L1/PD-L2 blockade in therapeutics for IVLBCL.

Immunohistochemical evaluation of PD-L1 expression in tumour and non-malignant HRS-like large cells may be useful for assessing either immune escape or immunodeficiency in their pathogenesis.

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Malignant peripheral nerve sheath tumor (MPNST) can be difficult to diagnose because it lacks specific immunohistochemical markers. S-100, which is a useful marker of MPNST, has limited diagnostic utility. Recent studies suggest that nestin, which is an intermediate filament protein, is expressed in neuroectodermal stem cells. The diagnostic utility of immunostains for nestin and three other neural markers (S-100, CD56 and protein gene product 9.5 (PGP 9.5)) were evaluated in 35 cases of MPNST and in other spindle cell tumors. All MPNST cases were strongly positive for nestin and had cytoplasmic staining. Stains for S-100, CD56, and PGP 9.5 were positive in fewer cases (17/35, 11/35, and 29/35 cases, respectively), and had less extensive staining. Nestin was negative in 10/10 leiomyomas, and weak nestin expression was seen in 10/10 schwannomas, 3/10 neurofibromas, 2/8 synovial sarcomas, 2/10 liposarcomas, 4/7 carcinosarcomas and 3/7 malignant fibrous histiocytomas. In contrast, strong nestin positivity was seen in 10/10 rhabdomyosarcomas, 15/19 leiomyosarcomas, and 9/9 desmoplastic melanomas. Nestin is more sensitive for MPNST than other neural markers and immunostains for nestin in combination with other markers could be useful in the diagnosis of MPNST.

Nodal T/NK-cell lymphoma may occupy the grey zone between extranodal nasal-type NK/T-cell lymphoma and nodal CTM+ PTCL in a spectrum of NK to T-cell lymphomas that are EBV+. The close relationship between NK/T-cell lymphomas and cytotoxic T-cell lymphomas was also substantiated.

We identified six patients with Epstein-Barr virus (EBV)-negative extranodal diffuse large B-cell lymphoma (DLBCL) and immunohistochemical expression of PD-L1 on their tumor cells by examining 283 DLBCL cases with the PD-L1 SP142 clone between 2015 and 2017. They consisted of two men and four women with a median age of 71 years, and were examined in an autopsy (n ¼ 1) and biopsies from the adrenal gland (n ¼ 2), skin (n ¼ 1), pelvic cavity (n ¼ 1), and kidney (n ¼ 1). All showed a monomorphic population of large transformed B-cells leading to diagnoses of DLBCL with two intravascular large B-cell lymphoma (IVLBCL) and one de novo CD5þ type and were featured by an invariable immunephenotype: CD3-, CD20þ, BCL-2þ, and MUM1þ. In addition, CD5 and CD10 were each detected in one case. All cases expressed PD-L1 on >10% to >90% of tumor cells, which was confirmed with two other PD-L1 antibodies (E1J2J and 28-8). Three untreated patients had a rapid, lethal clinical course within 7 months after diagnosis; while, the remaining three achieved complete remission after treatment and were alive at the last follow-up. We suggest immune evasion-related extranodal large B-cell lymphoma should be recognized beyond the currently identified entities of IVLBCL and de novo CD5þ DLBCL. K E Y W O R D S de novo CD5þ diffuse large B-cell lymphoma, extranodal diffuse large B-cell lymphoma, immune evasion, intravascular large B-cell lymphoma, neoplastic PD-L1 expression Pathology

Cell lines have been used for drug discovery as useful models of cancers; however, they do not recapitulate cancers faithfully, especially in the points of rapid growth rate and microenvironment independency. Consequently, the majority of conventional anti-cancer drugs are less sensitive to slow growing cells and do not target microenvironmental support, although most primary cancer cells grow slower than cell lines and depend on microenvironmental support. Here, we developed a novel high throughput drug screening system using patient-derived xenograft (PDX) cells of lymphoma that maintained primary cancer cell phenotype more than cell lines. The library containing 2613 known pharmacologically active substance and off-patent drugs were screened by this system. We could find many compounds showing higher cytotoxicity than conventional anti-tumor drugs. Especially, pyruvinium pamoate showed the highest activity and its strong anti-tumor effect was confirmed also in vivo. We extensively investigated its mechanism of action and found that it inhibited glutathione supply from stromal cells to lymphoma cells, implying the importance of the stromal protection from oxidative stress for lymphoma cell survival and a new therapeutic strategy for lymphoma. Our system introduces a primary cancer cell phenotype into cell-based phenotype screening and sheds new light on anti-cancer drug development.

After the disaster, hospitals located within the evacuation zone of a 30-km radius of the nuclear power plant were isolated. Maintenance of the health care system in such an event becomes difficult.