Posttransplant lymphoproliferative disorder of the central nervous system

Posttransplant lymphoproliferative disorder (PTLD) involves uncommon, severe complications following the transplantation of solid organs, bone marrow and stem cells. Despite comprising mainly lymphoid proliferations that are predominantly driven by lymphotropic Epstein-Barr virus (EBV) infections, PTLD often displays substantial morphologic heterogeneity that can pose diagnostic challenges. With the steady increase in transplantations accompanied by potent immunosuppressive therapy, it is important to heighten awareness of this entity among clinicians and pathologists. In comparison to systemic PTLD, cases that primarily manifest in the central nervous system (CNS) are reported to be more severe and to exhibit unique characteristics. So far, only isolated cases and small series have been reported describing CNS involvement in PTLD. In this article, we review the current knowledge, focusing on the histopathological features of primary CNS lymphoproliferative disorders following organ transplantation

Persistent fever, neck swelling, and small vessel vasculitis following tonsillectomy in a patient with Behçet's disease: a case report

INTRODUCTION: Behçet's disease commonly presents with recurrent oral and genital mucocutaneous ulcerations, uveitis and various skin manifestations. Other clinical symptoms include gastrointestinal ulcerations, arthritis, venous thrombosis, arterial aneurysms and central nervous system affection. Vasculitis underlies most clinical symptoms of Behçet's disease. CASE PRESENTATION: We report the case of a 62-year-old European Caucasian woman with Behçet's disease who presented with persistent fever and neck soft-tissue swelling, despite broad antibiotic treatment, two weeks after acute tonsillitis and a tonsillectomy. Diffuse epi- and mesopharyngeal swelling shown on a computed tomography scan of her neck and persistently elevated serum markers of inflammation initially prompted suspicion of an infectious etiology. Magnet resonance imaging of her neck and a neck tissue biopsy finally confirmed small vessel vasculitis involving skin, subcutaneous tissue and muscle. Considering the clinical presentation, past medical history and histological findings, we interpreted our patient's symptoms as a flare of Behçet's disease. Immunosuppressive treatment led to rapid clinical improvement. CONCLUSION: A patient with Behçet's disease developed small vessel vasculitis of the soft tissue of her neck after tonsillitis and a tonsillectomy. Infection and surgery probably triggered a flare of Behçet's disease

microRNA profiling in Epstein-Barr virus-associated B-cell lymphoma

The Epstein-Barr virus (EBV) is an oncogenic human Herpes virus found in ∼15% of diffuse large B-cell lymphoma (DLBCL). EBV encodes miRNAs and induces changes in the cellular miRNA profile of infected cells. MiRNAs are small, non-coding RNAs of ∼19-26 nt which suppress protein synthesis by inducing translational arrest or mRNA degradation. Here, we report a comprehensive miRNA-profiling study and show that hsa-miR-424, -223, -199a-3p, -199a-5p, -27b, -378, -26b, -23a, -23b were upregulated and hsa-miR-155, -20b, -221, -151-3p, -222, -29b/c, -106a were downregulated more than 2-fold due to EBV-infection of DLBCL. All known EBV miRNAs with the exception of the BHRF1 cluster as well as EBV-miR-BART15 and -20 were present. A computational analysis indicated potential targets such as c-MYB, LATS2, c-SKI and SIAH1. We show that c-MYB is targeted by miR-155 and miR-424, that the tumor suppressor SIAH1 is targeted by miR-424, and that c-SKI is potentially regulated by miR-155. Downregulation of SIAH1 protein in DLBCL was demonstrated by immunohistochemistry. The inhibition of SIAH1 is in line with the notion that EBV impedes various pro-apoptotic pathways during tumorigenesis. The down-modulation of the oncogenic c-MYB protein, although counter-intuitive, might be explained by its tight regulation in developmental processe

microRNA profiling in Epstein–Barr virus-associated B-cell lymphoma

The Epstein–Barr virus (EBV) is an oncogenic human Herpes virus found in ∼15% of diffuse large B-cell lymphoma (DLBCL). EBV encodes miRNAs and induces changes in the cellular miRNA profile of infected cells. MiRNAs are small, non-coding RNAs of ∼19–26 nt which suppress protein synthesis by inducing translational arrest or mRNA degradation. Here, we report a comprehensive miRNA-profiling study and show that hsa-miR-424, -223, -199a-3p, -199a-5p, -27b, -378, -26b, -23a, -23b were upregulated and hsa-miR-155, -20b, -221, -151-3p, -222, -29b/c, -106a were downregulated more than 2-fold due to EBV-infection of DLBCL. All known EBV miRNAs with the exception of the BHRF1 cluster as well as EBV-miR-BART15 and -20 were present. A computational analysis indicated potential targets such as c-MYB, LATS2, c-SKI and SIAH1. We show that c-MYB is targeted by miR-155 and miR-424, that the tumor suppressor SIAH1 is targeted by miR-424, and that c-SKI is potentially regulated by miR-155. Downregulation of SIAH1 protein in DLBCL was demonstrated by immunohistochemistry. The inhibition of SIAH1 is in line with the notion that EBV impedes various pro-apoptotic pathways during tumorigenesis. The down-modulation of the oncogenic c-MYB protein, although counter-intuitive, might be explained by its tight regulation in developmental processes

Tumor Cell Plasticity and Angiogenesis in Human Melanomas

Recent molecular studies provide evidence for a significant transcriptional plasticity of tumor cell subpopulations that facilitate an active contribution to tumor vasculature. This feature is accompanied by morphological changes both in vitro and in vivo. Herein, we investigated the morphological plasticity of tumor cells with special focus on vasculogenic mimicry and neovascularisation in human melanoma and mouse xenografts of human melanoma cell lines. In melanoma xenograft experiments, different vessel markers and green fluorescent protein expression were used to show how melanoma cells contribute to neovascularization. Additionally, we analyzed neovascularization in 49 primary melanomas and 175 melanoma metastases using immunostaining for blood (CD34) and lymphatic (D2–40) vessel-specific markers. We found significantly more lymphatic vessels in primary melanomas than in melanoma metastases (p<0.0001). In contrast to the near absence of lymphatic vessels within metastases, we found extensive blood micro-neovascularization. Blood micro-neovascularization was absent in micro metastases (less than 2 mm). A significant inverse correlation between Glut-1 expression (implying local hypoxia) and the presence of microvessels indicates their functional activity as blood vessels (p<0.0001). We suggest that the hypoxic microenvironment in metastases contributes to a phenotype switch allowing melanoma cells to physically contribute to blood vessel formation

Genetic Diversity of EBV-Encoded LMP1 in the Swiss HIV Cohort Study and Implication for NF-Κb Activation

Epstein-Barr virus (EBV) is associated with several types of cancers including Hodgkin's lymphoma (HL) and nasopharyngeal carcinoma (NPC). EBV-encoded latent membrane protein 1 (LMP1), a multifunctional oncoprotein, is a powerful activator of the transcription factor NF-κB, a property that is essential for EBV-transformed lymphoblastoid cell survival. Previous studies reported LMP1 sequence variations and induction of higher NF-κB activation levels compared to the prototype B95-8 LMP1 by some variants. Here we used biopsies of EBV-associated cancers and blood of individuals included in the Swiss HIV Cohort Study (SHCS) to analyze LMP1 genetic diversity and impact of sequence variations on LMP1-mediated NF-κB activation potential. We found that a number of variants mediate higher NF-κB activation levels when compared to B95-8 LMP1 and mapped three single polymorphisms responsible for this phenotype: F106Y, I124V and F144I. F106Y was present in all LMP1 isolated in this study and its effect was variant dependent, suggesting that it was modulated by other polymorphisms. The two polymorphisms I124V and F144I were present in distinct phylogenetic groups and were linked with other specific polymorphisms nearby, I152L and D150A/L151I, respectively. The two sets of polymorphisms, I124V/I152L and F144I/D150A/L151I, which were markers of increased NF-κB activation in vitro, were not associated with EBV-associated HL in the SHCS. Taken together these results highlighted the importance of single polymorphisms for the modulation of LMP1 signaling activity and demonstrated that several groups of LMP1 variants, through distinct mutational paths, mediated enhanced NF-κB activation levels compared to B95-8 LMP1

Peripheral giant-cell granuloma in peri-implant tissues

status: publishe