POLE-Mutant Colon Adenocarcinoma-Case Presentation and Histopathological Evaluation.

INTRODUCTION: POLE mutant phenotype in colon adenocarcinomas represents a rare molecular subtype. These tumours are generally responsive to immune-checkpoint inhibition therapy and, therefore, are currently considered as a subtype with good prognosis. We hereby present the first detailed case presentation of a POLE mutant colon adenocarcinoma with useful microscopic features. CASE REPORT: A 53-year-old male patient's colon adenocarcinoma histologically showed wide variety of growth patterns and massive intra- and peritumoural lymphocytic infiltrate. The majority of the tumour consisted of a high-grade component resembling medullary carcinoma of the colon, while approximately one-third of the tumour was composed of conventional areas exhibiting a tubular pattern. A minority of the tumour was constituted by poorly cohesive rhabdoid cells. Immunohistochemistry was performed, and colorectal origin was proven with CDX-2 and SATB2. Furthermore, proficiency in mismatch repair proteins and SMARCB1 deficiency was observed. The unusually high-grade colon adenocarcinoma, with areas mimicking medullary carcinoma, and generally aggressive morphology raised suspicion of microsatellite instability. The diverse morphology and the SMARCB1 deficiency also raised suspicion of ultramutation caused by POLE alteration. Next-generation sequencing panel confirmed a pathogenetic mutation in POLE exon 9: p.Pro286Arg, c.857C > G. DISCUSSION: The diverse, high-grade morphology and increased intratumoural lymphoid infiltration should raise suspicion for POLE-mutated adenocarcinoma during everyday histopathological practice. Mismatch repair proficiency results on immunohistochemistry should not determine the final diagnosis, as only a minor percentage of these tumours are MSI. In every case suspicious for POLE-mutated adenocarcinoma, a 500-cancer gene panel should be carried out.

NTRK-rearranged spindle cell sarcoma of the uterine cervix with a novel NUMA1::NTRK1 fusion.

NTRK-rearranged uterine sarcoma is a recently described entity that represents a subset of uterine sarcomas with distinct clinicopathological features. From a molecular point of view, this tumour is defined by NTRK gene rearrangement, resulting in overexpression or constitutive activation of Trk receptors. The presence of NTRK fusion is indicative of treatment response with a selective small-molecule inhibitor of the Trk kinases. Here, we report a case of an NTRK-rearranged sarcoma of the uterine cervix in a 43-year-old patient, measuring 80 mm in its largest dimension, with a novel NUMA1-NTRK1 fusion, not previously reported in NTRK-rearranged uterine sarcomas or other NTRK-rearranged tumours. The fusion, involving NUMA1 exon 14 (NM_006185.4) and NTRK1 exon 11 (NM_002529.4), was identified by next-generation sequencing (NGS) studies (FusionPlex Pan Solid Tumor v2 panel). Although the presence of NTRK fusion has been reported in a variety of neoplasms, a fusion involving NUMA1 (nuclear mitotic apparatus protein 1) and a tyrosine kinase partner has previously been reported in human neoplasms only in a handful of cases. The resulting fusion protein comprises the oligomerization domain of NUMA1, which is predicted to cause constant activation of the tyrosine kinase domain of NTRK1. The recognition and accurate diagnosis of these tumours are important due to the availability of potential targeted therapeutic options.

EGFR T790M Mutation Detection in Patients With Non-Small Cell Lung Cancer After First Line EGFR TKI Therapy: Summary of Results in a Three-Year Period and a Comparison of Commercially Available Detection Kits.

EGFR mutation in non-small cell lung cancer (NSCLC) offers a potential therapeutic target for tyrosine kinase inhibitor (TKI) therapy. The majority of these cases, however eventually develop therapy resistance, mainly by acquiring EGFR T790M mutation. Recently, third-generation TKIs have been introduced to overcome T790M mutation-related resistance. Cell free circulating tumor DNA (liquid biopsy) has emerged as a valuable alternative method for T790M mutation detection during patient follow up, when a tissue biopsy cannot be obtained for analysis. In this study, we summarized our experience with Super-ARMS EGFR Mutation Detection Kit (AmoyDx) on 401 samples of 242 NSCLC patients in a 3-year period in Hungary, comprising 364 plasma and 37 non-plasma samples. We also compared the performance of two commercially available detection kits, the cobas EGFR Mutation test v2 (Roche) and the Super-ARMS EGFR Mutation Detection Kit (AmoyDx). The same activating EGFR mutation was detected with the AmoyDx kit as in the primary tumor in 45.6% of the samples. T790M mutation was identified in 48.1% of the samples containing activating EGFR mutation. The detection rate of T790M mutation was not dependent on the DNA concentration of the plasma sample and there was no considerable improvement in mutation detection rate after a second, subsequent plasma sample. The concordance of EGFR activating mutation detection was 89% between the two methods, while this was 93% for T790M mutation detection. The AmoyDx kit, however showed an overall higher detection rate of T790M mutation compared to the cobas kit (p = 0.014). T790M mutation was detected at 29.8% of the patients if only plasma samples were available for analysis, while the detection rate was 70.2% in non-plasma samples. If the activating EGFR was detected in the plasma samples, the detection rate of T790M mutation was 42.4%. Although non-plasma samples provided a superior T790M mutation detection rate, we found that liquid biopsy can offer a valuable tool for T790M mutation detection, when a tissue biopsy is not available. Alternatively, a liquid biopsy can be used as a screening test, when re-biopsy should be considered in case of wild-type results.

Paraneoplastic pemphigus caused by pre-existing stroma-rich variant of Castleman disease: from a pathologist's point of view.

A young woman presented with mucocutaneous blisters and ulcerating lesions, and was diagnosed with erythrodermic pemphigus complicated by bronchiolitis obliterans. Her clinical condition did not improve on immunosuppressive therapy. She had a history of an asymptomatic retroperitoneal mass, presumed to be a dermoid cyst, followed up clinically. Due to the pre-existing nature of the retroperitoneal mass, the paraneoplastic nature of the pemphigus was initially not recognised, but after a multidisciplinary team meeting a biopsy was performed. Histology revealed a rare stroma-rich variant of Castleman disease with a prominent stroma demonstrating a myoid phenotype. Resection of the retroperitoneal tumour resulted in resolution of the cutaneous blisters. This emphasises the importance to consider paraneoplastic disease in treatment-resistant pemphigus as surgical removal of the tumour forms the mainstay of therapy. The differential diagnosis should include Castleman disease and careful evaluation of histology is essential with the awareness of this rare stroma-rich variant.

Transcriptomic Analyses of MYCN-Regulated Genes in Anaplastic Wilms' Tumour Cell Lines Reveals Oncogenic Pathways and Potential Therapeutic Vulnerabilities.

The MYCN proto-oncogene is deregulated in many cancers, most notably in neuroblastoma, where MYCN gene amplification identifies a clinical subset with very poor prognosis. Gene expression and DNA analyses have also demonstrated overexpression of MYCN mRNA, as well as focal amplifications, copy number gains and presumptive change of function mutations of MYCN in Wilms' tumours with poorer outcomes, including tumours with diffuse anaplasia. Surprisingly, however, the expression and functions of the MYCN protein in Wilms' tumours still remain obscure. In this study, we assessed MYCN protein expression in primary Wilms' tumours using immunohistochemistry of tissue microarrays. We found MYCN protein to be expressed in tumour blastemal cells, and absent in stromal and epithelial components. For functional studies, we used two anaplastic Wilms' tumour cell-lines, WiT49 and 17.94, to study the biological and transcriptomic effects of MYCN depletion. We found that MYCN knockdown consistently led to growth suppression but not cell death. RNA sequencing identified 561 MYCN-regulated genes shared by WiT49 and 17.94 cell-lines. As expected, numerous cellular processes were downstream of MYCN. MYCN positively regulated the miRNA regulator and known Wilms' tumour oncogene LIN28B, the genes encoding methylosome proteins PRMT1, PRMT5 and WDR77, and the mitochondrial translocase genes TOMM20 and TIMM50. MYCN repressed genes including the developmental signalling receptor ROBO1 and the stromal marker COL1A1. Importantly, we found that MYCN also repressed the presumptive Wilms' tumour suppressor gene REST, with MYCN knockdown resulting in increased REST protein and concomitant repression of RE1-Silencing Transcription factor (REST) target genes. Together, our study identifies regulatory axes that interact with MYCN, providing novel pathways for potential targeted therapeutics for poor-prognosis Wilms' tumour.

A report of a patient presenting with three metachronous 13q14LOH mesenchymal tumours: spindle cell lipoma, cellular angiofibroma and mammary myofibroblastoma.

Spindle cell lipoma, cellular angiofibroma and mammary myofibroblastoma are mesenchymal tumours that have overlapping morphological and immunophenotypic features. Aberrations in chromosome 13q14 have been identified as a recurrent feature. We report a unique case of a 69-year-old woman who metachronously developed all three tumours. She developed a peri-urethral and a recurrent peri-vaginal cellular angiofibroma at age 54 and 57, respectively, a spindle cell lipoma at age 62 and a mammary myofibroblastoma at age 69. Dual-colour interphase fluorescent in situ hybridisation (FISH) revealed losses of RB1 and FOXO1 (13q14LOH [loss of heterozygosity]) within neoplastic cells. There was also loss of retinoblastoma (Rb) protein expression. To our knowledge, this is the first report of these three tumours arising in the same patient. The genetic link between these tumours supports the hypothesis that they may arise from the same progenitor cells. However, further research is required to elucidate the precise pathogenetic link.

Two cases of rare HHV8-driven intravascular lymphoma with synchronous Kaposi sarcoma, both diagnosed at autopsy in renal transplant recipients.

We present the first report of two rare yet remarkably similar autopsy cases of Kaposi sarcoma (KS) and intravascular human herpesvirus 8 (HHV8) positive lymphoproliferative disorder in renal transplant patients. It is well established that HHV8 infection causes Kaposi sarcoma (KS). More recently, it is recognized that HHV8 is also related to several lymphoproliferative conditions. These are poorly characterized and often difficult to diagnose. In both cases described herein, the diagnoses of multifocal hepatic KS and intravascular HHV8 positive (EBV negative) systemic diffuse large B-cell lymphoma, NOS were made at autopsy. Given the findings we describe in cases with fatal outcomes, we discuss the implications of HHV8 screening in solid allograft recipients.

Increased Efficacy of Histone Methyltransferase G9a Inhibitors Against MYCN-Amplified Neuroblastoma.

Targeted inhibition of proteins modulating epigenetic changes is an increasingly important priority in cancer therapeutics, and many small molecule inhibitors are currently being developed. In the case of neuroblastoma (NB), a pediatric solid tumor with a paucity of intragenic mutations, epigenetic deregulation may be especially important. In this study we validate the histone methyltransferase G9a/EHMT2 as being associated with indicators of poor prognosis in NB. Immunological analysis of G9a protein shows it to be more highly expressed in NB cell-lines with MYCN amplification, which is a primary determinant of dismal outcome in NB patients. Furthermore, G9a protein in primary tumors is expressed at higher levels in poorly differentiated/undifferentiated NB, and correlates with high EZH2 expression, a known co-operative oncoprotein in NB. Our functional analyses demonstrate that siRNA-mediated G9a depletion inhibits cell growth in all NB cell lines, but, strikingly, only triggers apoptosis in NB cells with MYCN amplification, suggesting a synthetic lethal relationship between G9a and MYCN. This pattern of sensitivity is also evident when using small molecule inhibitors of G9a, UNC0638, and UNC0642. The increased efficacy of G9a inhibition in the presence of MYCN-overexpression is also demonstrated in the SHEP-21N isogenic model with tet-regulatable MYCN. Finally, using RNA sequencing, we identify several potential tumor suppressor genes that are reactivated by G9a inhibition in NB, including the CLU, FLCN, AMHR2, and AKR1C1-3. Together, our study underlines the under-appreciated role of G9a in NB, especially in MYCN-amplified tumors.

A Wnt-BMP4 Signaling Axis Induces MSX and NOTCH Proteins and Promotes Growth Suppression and Differentiation in Neuroblastoma.

The Wnt and bone morphogenetic protein (BMP) signaling pathways are known to be crucial in the development of neural crest lineages, including the sympathetic nervous system. Surprisingly, their role in paediatric neuroblastoma, the prototypic tumor arising from this lineage, remains relatively uncharacterised. We previously demonstrated that Wnt/b-catenin signaling can have cell-type-specific effects on neuroblastoma phenotypes, including growth inhibition and differentiation, and that BMP4 mRNA and protein were induced by Wnt3a/Rspo2. In this study, we characterised the phenotypic effects of BMP4 on neuroblastoma cells, demonstrating convergent induction of MSX homeobox transcription factors by Wnt and BMP4 signaling and BMP4-induced growth suppression and differentiation. An immunohistochemical analysis of BMP4 expression in primary neuroblastomas confirms a striking absence of BMP4 in poorly differentiated tumors, in contrast to a high expression in ganglion cells. These results are consistent with a tumor suppressive role for BMP4 in neuroblastoma. RNA sequencing following BMP4 treatment revealed induction of Notch signaling, verified by increases of Notch3 and Hes1 proteins. Together, our data demonstrate, for the first time, Wnt-BMP-Notch signaling crosstalk associated with growth suppression of neuroblastoma.

Cell block processing is optimal for assessing endoscopic ultrasound fine needle aspiration specimens of pancreatic mucinous cysts.

AIMS: The cell block technique for assessing endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) specimens from pancreatic mucinous cystic lesions (MCLs) was systematically evaluated for the first time, including comparisons with three traditional methods of assessing such specimens. METHODS: The prospective arm comprised EUS-FNA specimens from EUS-suspected pancreatic MCLs. The retrospective arm comprised EUS-FNA specimens from pancreatic MCLs surgically resected before the study start. For each specimen, these data points were collected: macroscopic likelihood of mucin, cyst fluid carcinoembryonic antigen (CEA) level and presence of mucin in air-dried, direct smears and in cell block preparations. RESULTS: The prospective and retrospective arms of the study comprised 80 and 30 EUS-FNA specimens, respectively. Seven prospective cases led to surgical resections during the study, and therefore, 37 EUS-FNA specimens were confirmed to have originated from MCLs. In the prospective arm, macroscopic mucin was suspected, cyst fluid CEA level exceeded 192 ng/mL, mucin was detected in direct smears and cell block preparations in 78%, 30%, 39% and 73% of cases, respectively. Of the 37 specimens confirmed to originate from MCLs, macroscopic mucin assessment, cyst fluid CEA level, direct smear mucin assessment and cell block mucin assessment had sensitivities for diagnosing MCL of 87%, 45%, 45% and 81%, respectively. CONCLUSIONS: Cell block preparations are as likely to identify mucin from pancreatic MCLs as macroscopic assessment but are twice as likely to diagnose MCL than direct smears and fluid CEA biochemistry. The cell block technique is easy for sample collection and processing especially because these are identical for solid and cystic pancreatic lesions.

Two cases of rare HHV8-driven intravascular lymphoma with synchronous Kaposi sarcoma, both diagnosed at autopsy in renal transplant recipients

We present the first report of two rare yet remarkably similar autopsy cases of Kaposi sarcoma (KS) and intravascular human herpesvirus 8 (HHV8) positive lymphoproliferative disorder in renal transplant patients. It is well established that HHV8 infection causes Kaposi sarcoma (KS). More recently, it is recognized that HHV8 is also related to several lymphoproliferative conditions. These are poorly characterized and often difficult to diagnose. In both cases described herein, the diagnoses of multifocal hepatic KS and intravascular HHV8 positive (EBV negative) systemic diffuse large B-cell lymphoma, NOS were made at autopsy. Given the findings we describe in cases with fatal outcomes, we discuss the implications of HHV8 screening in solid allograft recipients.

Targeting Angiogenesis in Prostate Cancer.

Prostate cancer is the most commonly diagnosed cancer among men in the Western world. Although localized disease can be effectively treated with established surgical and radiopharmaceutical treatments options, the prognosis of castration-resistant advanced prostate cancer is still disappointing. The objective of this study was to review the role of angiogenesis in prostate cancer and to investigate the effectiveness of anti-angiogenic therapies. A literature search of clinical trials testing the efficacy of anti-angiogenic therapy in prostate cancer was performed using Pubmed. Surrogate markers of angiogenic activity (microvessel density and vascular endothelial growth factor A (VEGF-A) expression) were found to be associated with tumor grade, metastasis, and prognosis. Six randomizedstudies were included in this review: two phase II trials on localized and hormone-sensitive disease (n = 60 and 99 patients) and four phase III trials on castration-resistant refractory disease (n = 873 to 1224 patients). Although the phase II trials showed improved relapse-free survival and stabilisation of the disease, the phase III trials found increased toxicity and no significant improvement in overall survival. Although angiogenesis appears to have an important role in prostate cancer, the results of anti-angiogenic therapy in castration-resistant refractory disease have hitherto been disappointing. There are various possible explanations for this lack of efficacy in castration-resistant refractory disease: redundancy of angiogenic pathways, molecular heterogeneity of the disease, loss of tumor suppressor protein phosphatase and tensin homolog (PTEN) expression as well as various VEGF-A splicing isoforms with pro- and anti-angiogenic activity. A better understanding of the molecular mechanisms of angiogenesis may help to develop effective anti-angiogenic therapy in prostate cancer.

Computer Aided Classification of Neuroblastoma Histological Images Using Scale Invariant Feature Transform with Feature Encoding.

Neuroblastoma is the most common extracranial solid malignancy in early childhood. Optimal management of neuroblastoma depends on many factors, including histopathological classification. Although histopathology study is considered the gold standard for classification of neuroblastoma histological images, computers can help to extract many more features some of which may not be recognizable by human eyes. This paper, proposes a combination of Scale Invariant Feature Transform with feature encoding algorithm to extract highly discriminative features. Then, distinctive image features are classified by Support Vector Machine classifier into five clinically relevant classes. The advantage of our model is extracting features which are more robust to scale variation compared to the Patched Completed Local Binary Pattern and Completed Local Binary Pattern methods. We gathered a database of 1043 histologic images of neuroblastic tumours classified into five subtypes. Our approach identified features that outperformed the state-of-the-art on both our neuroblastoma dataset and a benchmark breast cancer dataset. Our method shows promise for classification of neuroblastoma histological images.

Wnt Signalling Drives Context-Dependent Differentiation or Proliferation in Neuroblastoma.

Neuroblastoma is one of the commonest and deadliest solid tumours of childhood, and is thought to result from disrupted differentiation of the developing sympathoadrenergic lineage of the neural crest. Neuroblastoma exhibits intra- and intertumoural heterogeneity, with high risk tumours characterised by poor differentiation, which can be attributable to MYCN-mediated repression of genes involved in neuronal differentiation. MYCN is known to co-operate with oncogenic signalling pathways such as Alk, Akt and MEK/ERK signalling, and, together with c-MYC has been shown to be activated by Wnt signalling in various tissues. However, our previous work demonstrated that Wnt3a/Rspo2 treatment of some neuroblastoma cell lines can, paradoxically, decrease c-MYC and MYCN proteins. This prompted us to define the neuroblastoma-specific Wnt3a/Rspo2-driven transcriptome using RNA sequencing, and characterise the accompanying changes in cell biology. Here we report the identification of ninety Wnt target genes, and show that Wnt signalling is upstream of numerous transcription factors and signalling pathways in neuroblastoma. Using live-cell imaging, we show that Wnt signalling can drive differentiation of SK-N-BE(2)-C and SH-SY5Y cell-lines, but, conversely, proliferation of SK-N-AS cells. We show that cell-lines that differentiate show induction of pro-differentiation BMP4 and EPAS1 proteins, which is not apparent in the SK-N-AS cells. In contrast, SK-N-AS cells show increased CCND1, phosphorylated RB and E2F1 in response to Wnt3a/Rspo2, consistent with their proliferative response, and these proteins are not increased in differentiating lines. By meta-analysis of the expression of our 90 genes in primary tumour gene expression databases, we demonstrate discrete expression patterns of our Wnt genes in patient cohorts with different prognosis. Furthermore our analysis reveals interconnectivity within subsets of our Wnt genes, with one subset comprised of novel putative drivers of neuronal differentiation repressed by MYCN. Assessment of ß-catenin immunohistochemistry shows high levels of ß-catenin in tumours with better differentiation, further supporting a role for canonical Wnt signalling in neuroblastoma differentiation.

The small molecule inhibitor YK-4-279 disrupts mitotic progression of neuroblastoma cells, overcomes drug resistance and synergizes with inhibitors of mitosis.

Neuroblastoma is a biologically and clinically heterogeneous pediatric malignancy that includes a high-risk subset for which new therapeutic agents are urgently required. As well as MYCN amplification, activating point mutations of ALK and NRAS are associated with high-risk and relapsing neuroblastoma. As both ALK and RAS signal through the MEK/ERK pathway, we sought to evaluate two previously reported inhibitors of ETS-related transcription factors, which are transcriptional mediators of the Ras-MEK/ERK pathway in other cancers. Here we show that YK-4-279 suppressed growth and triggered apoptosis in nine neuroblastoma cell lines, while BRD32048, another ETV1 inhibitor, was ineffective. These results suggest that YK-4-279 acts independently of ETS-related transcription factors. Further analysis reveals that YK-4-279 induces mitotic arrest in prometaphase, resulting in subsequent cell death. Mechanistically, we show that YK-4-279 inhibits the formation of kinetochore microtubules, with treated cells showing a broad range of abnormalities including multipolar, fragmented and unseparated spindles, together leading to disrupted progression through mitosis. Notably, YK-4-279 does not affect microtubule acetylation, unlike the conventional mitotic poisons paclitaxel and vincristine. Consistent with this, we demonstrate that YK-4-279 overcomes vincristine-induced resistance in two neuroblastoma cell-line models. Furthermore, combinations of YK-4-279 with vincristine, paclitaxel or the Aurora kinase A inhibitor MLN8237/Alisertib show strong synergy, particularly at low doses. Thus, YK-4-279 could potentially be used as a single-agent or in combination therapies for the treatment of high-risk and relapsing neuroblastoma, as well as other cancers.

The mutational frequency of BRAF and KRAS in low-grade serous testicular neoplasms-a case series.

AIMS: Low-grade serous neoplasms of the testis are rare neoplasms that show striking morphological similarities with the better-understood ovarian neoplasms. This study is to see if there are similar molecular abnormalities in these two tumours. The cell of origin, relationship with serous ovarian tumour and the pathogenesis of these neoplasms are not fully established. METHODS AND RESULTS: As low-grade serous ovarian neoplasms are known to harbour mutations in the MAPK pathway, we investigated the involvement of BRAF and KRAS mutations in low-grade testicular serous tumour by performing mutational analysis of seven cases. Mutational analysis was performed by melting curve analysis followed by bidirectional sequencing. Our findings showed BRAF and/or KRAS mutations in three of the seven cases, which is similar to the proportions reported in low-grade ovarian serous neoplasms. Of these three cases, one showed co-mutation of BRAF and KRAS. CONCLUSION: The findings of this study are in support of a role of aberrant signalling of the MAPK pathway in the pathogenesis of low-grade serous testicular neoplasms, and provide a genetic link between low-grade testicular and ovarian serous tumours.