Next-generation sequencing in the diagnosis of non-cirrhotic splanchnic vein thrombosis

Portal vein thrombosis: diagnosis, management, and endpoints for future clinical studies

Portal vein thrombosis (PVT) refers to the development of a non-malignant obstruction of the portal vein, its branches, its radicles, or a combination. This Review first provides a comprehensive overview of all aspects of PVT, namely the specifics of the portal venous system, the risk factors for PVT, the pathophysiology of portal hypertension in PVT, the interest in non-invasive tests, as well as therapeutic approaches including the effect of treating risk factors for PVT or cause of cirrhosis, anticoagulation, portal vein recanalisation by interventional radiology, and prevention and management of variceal bleeding in patients with PVT. Specific issues are also addressed including portal cholangiopathy, mesenteric ischaemia and intestinal necrosis, quality of life, fertility, contraception and pregnancy, and PVT in children. This Review will then present endpoints for future clinical studies in PVT, both in patients with and without cirrhosis, agreed by a large panel of experts through a Delphi consensus process. These endpoints include classification of portal vein thrombus extension, classification of PVT evolution, timing of assessment of PVT, and global endpoints for studies on PVT including clinical outcomes. These endpoints will help homogenise studies on PVT and thus facilitate reporting, comparison between studies, and validation of future studies and trials on PVT.

B-cell hub genes play a cardiovascular pathogenic role of in childhood obesity and Kawasaki disease as revealed by transcriptomics-based analyses

The study aims to explore the central genes that Kawasaki disease (KD) and Obesity (OB) may jointly contribute to coronary artery disease. Investigating single-cell datasets (GSE168732 and GSE163830) from a comprehensive gene expression database, we identified characteristic immune cell subpopulations in KD and OB. B cells emerged as the common immune cell characteristic subgroup in both conditions. Subsequently, we analyzed RNA sequencing datasets (GSE18606 and GSE87493) to identify genes associated with B-cell subpopulations in KD and OB. Lastly, a genome-wide association study and Mendelian randomization were conducted to substantiate the causal impact of these core genes on myocardial infarction. Quantitative real-time PCR (qRT-PCR) to validate the expression levels of hub genes in KD and OB. The overlapping characteristic genes of B cell clusters in both KD and OB yielded 70 shared characteristic genes. PPI analysis led to the discovery of eleven key genes that significantly contribute to the crosstalk. Employing receiver operating characteristic analysis, we evaluated the specificity and sensitivity of these core genes and scored them using Cytoscape software. The inverse variance weighting analysis suggested an association between TNFRSF17 and myocardial infarction risk, with an odds ratio of 0.9995 (95% CI = 0.9990-1.0000, p = 0.049). By employing a single-cell combined transcriptome data analysis, we successfully pinpointed central genes associated with both KD and OB. The implications of these findings extend to shedding light on the increased risk of coronary artery disease resulting from the co-occurrence of OB and KD.

Current concepts in the management of non-cirrhotic non-malignant portal vein thrombosis

Non-cirrhotic non-malignant portal vein thrombosis (NCPVT) is an uncommon condition characterised by thrombosis of the portal vein, with or without extension into other mesenteric veins, in the absence of cirrhosis or intra-abdominal malignancy. Complications can include intestinal infarction, variceal bleeding and portal biliopathy. In this article, we address current concepts in the management of NCPVT including identification of risk factors, classification and treatment, and review the latest evidence on medical and interventional management options.

Recurrent splanchnic and extrasplanchnic thrombotic events in patients with non-cirrhotic portal vein thrombosis associated with local factors

BACKGROUND & AIMS

One-third of non-cirrhotic portal vein thrombosis (NCPVT) cases are associated with local factors. The risk of rethrombosis after anticoagulation withdrawal is unknown. We aimed to determine factors associated with new splanchnic or extrasplanchnic thrombotic events in this setting.

METHODS

We performed a retrospective study including cases of recent NCPVT associated with local factors. High- and low-risk prothrombotic factors, prespecified according to RIPORT study criteria, were assessed. Univariate and multivariate Cox models assessed the influence of different variables on the occurrence of new thrombotic events.

RESULTS

At baseline, 83/154 (53.9%) patients had at least one prothrombotic factor including 50 (32.5%) with a high-risk and 33 (21.4%) with a low-risk prothrombotic factor. Oestrogen-containing contraception was discontinued in all patients. During follow-up, 63/140 (45%) patients had at least one prothrombotic factor, including 47 (33.6%) with a high-risk and 16 (11.4%) with a low-risk prothrombotic factor. Seventeen new thrombotic events occurred after a median follow-up of 52 (IQR 14-62) (min-max 3.0-69.0) months. New thromboses were associated with high-risk factors (hazard ratio [HR] 3.817, 95% CI 1.303-11.180, p = 0.015), but were inversely related to recanalization (HR 0.222, 95% CI 0.078-0.635, p = 0.005) and anticoagulation (HR 0.976, 95% CI 0.956-0.995, p = 0.016). When a high-risk factor was present a new thrombotic event occurred in 7.4%, 14.6%, 14.6% and 28.8% of patients at 1, 3, 5 and 7 years under anticoagulants, respectively, compared to 21.2%, 21.2%, 58% and 58% without anticoagulants, respectively.

CONCLUSIONS

In cases of recent NCPVT associated with local factors, high-risk factors for thrombosis are associated with new thrombotic events. Permanent anticoagulation appears beneficial in this high-risk situation.

IMPACT AND IMPLICATIONS

In non-cirrhotic portal vein thrombosis (NCPVT) associated with local factors, systematic screening for prothrombotic factors is recommended, but the prevalence of the latter is not clearly established, and the risk of recurrent intra or extrasplanchnic thromboembolism is poorly described. Thus, interest in permanent anticoagulation remains. NCPVT associated with local factors is a matter of concern for hepatologists, gastroenterologists and digestive surgeons. Due to a lack of knowledge, practices are heterogeneous. Our findings highlight that systematic screening for prothrombotic factors in NCPVT is needed even when associated with local factors, as it may justify long-term anticoagulation for the prevention of new intra or extrasplanchnic thrombotic events in at least one-third of cases. The interest in long-term anticoagulation should be investigated prospectively in the absence of high-risk prothrombotic factors.

CLINICAL TRIAL NUMBER

NCT0536064.

Cancer-associated splanchnic vein thrombosis: Clinical implications and management considerations

Splanchnic vein thrombosis (SVT), a thrombosis which involves the portal, mesenteric, and splenic veins, and the Budd-Chiari syndrome, represents an uncommon type of venous thromboembolism (VTE). Like with deep vein thrombosis of the lower extremities and pulmonary embolism, ample evidence suggests a significant association between SVT and cancer, particularly intra-abdominal solid malignancies (e.g. hepatobiliary and pancreatic cancers) and myeloproliferative neoplasms (MPN). Clinical symptoms of SVT in cancer patients can be ambiguous, and frequently attributed to the primary cancer itself. Alternatively, SVT may be asymptomatic and detected incidentally during cancer staging or follow-up evaluations. SVT can also precede the diagnosis of cancer and has been associated with poorer outcomes in patients with liver or pancreatic cancers. Therefore, an unprovoked SVT warrants a thorough evaluation for an underlying malignancy or MPN. Cancer-associated SVT carries a high risk of VTE extension, recurrence and bleeding. Extended anticoagulant treatment is often required in the absence of a high bleeding risk. Guidelines suggest treatment with either low molecular weight heparin (LMWH) or direct oral anticoagulants (DOACs), although available data on the safety and effectiveness of DOACs in these patients is limited. This comprehensive review outlines the epidemiology, pathogenesis, risk factors, and diagnosis of cancer-associated SVT and underscores the importance of comprehensive patient evaluation and evidence-based management.

Exploring the Molecular Aspects of Myeloproliferative Neoplasms Associated with Unusual Site Vein Thrombosis: Review of the Literature and Latest Insights

Myeloproliferative neoplasms (MPNs) are the leading causes of unusual site thrombosis, affecting nearly 40% of individuals with conditions like Budd-Chiari syndrome or portal vein thrombosis. Diagnosing MPNs in these cases is challenging because common indicators, such as spleen enlargement and elevated blood cell counts, can be obscured by portal hypertension or bleeding issues. Recent advancements in diagnostic tools have enhanced the accuracy of MPN diagnosis and classification. While bone marrow biopsies remain significant diagnostic criteria, molecular markers now play a pivotal role in both diagnosis and prognosis assessment. Hence, it is essential to initiate the diagnostic process for splanchnic vein thrombosis with a JAK2 V617F mutation screening, but a comprehensive approach is necessary. A multidisciplinary strategy is vital to accurately determine the specific subtype of MPNs, recommend additional tests, and propose the most effective treatment plan. Establishing specialized care pathways for patients with splanchnic vein thrombosis and underlying MPNs is crucial to tailor management approaches that reduce the risk of hematological outcomes and hepatic complications.

The molecular landscape of myeloproliferative neoplasms associated with splanchnic vein thrombosis: Current perspective

BCR::ABL1-negative myeloproliferative neoplasms (MPNs) are classically represented by polycythemia vera, essential thrombocythemia, and primary myelofibrosis. BCR::ABL1-negative MPNs are significantly associated with morbidity and mortality related to an increased risk of thrombo-hemorrhagic events. They show a consistent association with splanchnic vein thrombosis (SVT), either represented by the portal, mesenteric or splenic vein thrombosis, or Budd-Chiari Syndrome. SVT is also a frequent presenting manifestation of MPN. MPNs associated with SVT show a predilection for younger women, high association with JAK2V617F mutation, low JAK2V617F variant allele frequency (generally <10 %), and low rates of CALR, MPL, or JAK2 exon 12 mutations. Next-Generation Sequencing techniques have contributed to deepening our knowledge of the molecular landscape of such cases, with potential diagnostic and prognostic implications. In this narrative review, we analyze the current perspective on the molecular background of MPN associated with SVT, pointing as well future directions in this field.

Budd-Chiari syndrome in children: Challenges and outcome

Budd-Chiari syndrome (BCS) is an uncommon disease of the liver, characterised by obstruction of the hepatic venous outflow tract. The etiological spectrum of BCS as well as venous obstruction pattern show wide geographical and demographic variations across the globe. Compared to adults with BCS, children have primary BCS as the predominant etiology, earlier clinical presentation, and hence better treatment outcome. Underlying prothrombotic conditions play a key role in the etiopathogenesis of BCS, though work-up for the same is often unyielding in children. Use of next-generation sequencing in addition to conventional tests for thrombophilia leads to better diagnostic yield. In recent years, advances in radiological endovascular intervention techniques have revolutionized the treatment and outcome of BCS. Various non-invasive markers of fibrosis like liver and splenic stiffness measurement are being increasingly used to assess treatment response. Elastography techniques provide a novel non-invasive tool for measuring liver and splenic stiffness. This article reviews the diagnostic and therapeutic advances and challenges in children with BCS.

Splanchnic Vein Thrombosis in Myelofibrosis-An Underappreciated Hallmark of Disease Phenotype

Splanchnic vein thrombosis (SVT) encompasses thrombosis in the vessels of the splanchnic basin and has a relatively rare occurrence with a reported frequency in the general population of 1-2%. An episode of seemingly unprovoked SVT almost always triggers a diagnostic work-up for a Philadelphia chromosome-negative myeloproliferative neoplasm (MPN), since atypical site thrombosis is a hallmark of MPN-associated thrombophilia. Primary myelofibrosis (PMF) is a rare MPN with an estimated incidence between 0.1 and 1/100,000 per year. Although prothrombotic tendency in PMF is not envisioned as a subject of specific therapeutic management, unlike other MPNs, such as polycythemia vera (PV) and essential thrombocythemia (ET), thrombotic risk and SVT prevalence in PMF may be comparably high. Additionally, unlike PV and ET, SVT development in PMF may depend more on procoagulant mechanisms involving endothelium than on blood cell activation. Emerging results from registry data also suggest that PMF patients with SVT may exhibit lower risk and better prognosis, thus highlighting the need for better thrombotic risk stratification and identifying a subset of patients with potential benefit from antithrombotic prophylaxis. This review highlights specific epidemiological, pathogenetic, and clinical features pertinent to SVT in myelofibrosis.

Pathological and genomic features of myeloproliferative neoplasms associated with splanchnic vein thrombosis in a single-center cohort

Here, we reviewed clinical-morphological data and investigated mutational profiles by NGS in a single-center series of 58 consecutive MPN-SVT patients admitted to our hospital between January 1979 and November 2021. We identified 15.5% of PV, 13.8% of ET, 34.5% of PMF, 8.6% of SMF and 27.6% of MPN-U. Most cases (84.5%) carried JAK2V617F mutation, while seven patients were characterized by other molecular markers, namely MPL in four and CALR mutations in three cases. NGS was performed in 54 (93.1%) cases: the most frequent additional mutations were found in TET2 (27.8%) and DNMT3A (16.7%) genes, whereas 25 (46.3%) patients had no additional mutation. Cases with JAK2V617F homozygosity had a higher median number of additional mutations than those with low allele burden. More importantly, all cases of leukemic evolution were characterized by a higher median number of co-mutations, and a co-mutational pattern of high-risk lesions, such as truncating mutations of ASXL1, bi-allelic TP53 loss, and CSMD1 mutations. Nevertheless, no difference was found between cases with and without additional somatic mutations regarding fibrotic progression, SVT recurrence, other thrombo-hemorrhagic complications, or death. After a median follow-up of 7.1 years, ten deaths were recorded; fibrotic progression/leukemic evolution was ascertained in one (1.7%) and six (10.3%) patients, respectively, while 22 (37.9%) patients suffered from recurrent thrombosis. In conclusion, our data underline the importance of using NGS analysis in the management of MPN-related SVT as it can support the MPN diagnosis, particularly in "triple-negative" cases, and provide additional information with potential consequences on prognosis and therapeutic strategies.

Management of splanchnic vein thrombosis

The expression splanchnic vein thrombosis encompasses Budd-Chiari syndrome and portal vein thrombosis. These disorders have common characteristics: they are both rare diseases which can cause portal hypertension and its complications. Budd-Chiari syndrome and portal vein thrombosis in the absence of underlying liver disease share many risk factors, among which myeloproliferative neoplasms represent the most common; a rapid comprehensive work-up for risk factors of thrombosis is needed in these patients. Long-term anticoagulation is indicated in most patients. Portal vein thrombosis can also develop in patients with cirrhosis and in those with porto-sinusoidal vascular liver disease. The presence and nature of underlying liver disease impacts the management of portal vein thrombosis. Indications for anticoagulation in patients with cirrhosis are growing, while transjugular intrahepatic portosystemic shunt is now a second-line option. Due to the rarity of these diseases, studies yielding high-grade evidence are scarce. However, collaborative studies have provided new insight into the management of these patients. This article focuses on the causes, diagnosis, and management of patients with Budd-Chiari syndrome, portal vein thrombosis without underlying liver disease, or cirrhosis with non-malignant portal vein thrombosis.

Myeloproliferative neoplasms and splanchnic vein thrombosis: Contemporary diagnostic and therapeutic strategies

Myeloproliferative neoplasms (MPNs) are the most common etiologies of primary splanchnic vein thrombosis, present in almost forty percent of patients with Budd-Chiari syndrome or portal vein thrombosis. Diagnosis of MPNs can be difficult in these patients because key characteristics, such as elevated blood cell counts and splenomegaly, are confounded by portal hypertension or bleeding complications. In recent years, diagnostic tools have improved to provide more accurate diagnosis and classification of MPNs. Although bone marrow biopsy findings remain a major diagnostic criterion, molecular markers are playing an increasing role not only in diagnosis but also in better estimating prognosis. Therefore, though screening for JAK2V617F mutation should be the starting point of the diagnostic workup performed in all patients with splanchnic vein thrombosis, a multidisciplinary approach is needed to accurately diagnose the subtype of myeloproliferative neoplasm, recommend the useful additional tests (bone marrow biopsy, search for an additional mutation using targeted next-generation sequencing), and suggest the best treatment strategy. Indeed, providing a specific expert care pathway for patients with splanchnic vein thrombosis and underlying myeloproliferative neoplasm is crucial to determine the optimal management to reduce the risk of both hematological and hepatic complications.

Shedding Light on the Pathogenesis of Splanchnic Vein Thrombosis

Splanchnic vein thrombosis is a rare but potentially life-threatening manifestation of venous thromboembolism, with challenging implications both at the pathological and therapeutic level. It is frequently associated with liver cirrhosis, but it could also be provoked by myeloproliferative disorders, cancer of various gastroenterological origin, abdominal infections and thrombophilia. A portion of splanchnic vein thrombosis is still classified as idiopathic. Here, we review the mechanisms of splanchnic vein thrombosis, including new insights on the role of clonal hematopoiesis in idiopathic SVT pathogenesis, with important implications from the therapeutic standpoint.

Incidence and factors predictive of recurrent thrombosis in people with non-cirrhotic portal vein thrombosis

BACKGROUND & AIMS

Clinical guidelines do not recommend long-term anticoagulation in non-cirrhotic splanchnic vein thrombosis (NC-SVT) without underlying thrombophilia because it is assumed that there is a very low risk of recurrent thrombosis (RT). Our first aim was to describe the incidence of RT in people with NC-SVT without an indication for long-term anticoagulation. The second aim was to identify RT risk factors and afterwards verify them in a validation cohort.

METHODS

This is a multicentre, retrospective observational study evaluating risk factors for RT in 64 people with NC-SVT of idiopathic/local factor aetiology. In a subgroup of 48 individuals, the potential value of additional thrombophilic parameters to predict RT was analysed. Findings were validated in 70 individuals with idiopathic/local factor NC-SVT.

RESULTS

Of the 64 participants in the training cohort, 17 (26%) presented splanchnic and/or extrasplanchnic RT (overall-RT) during follow-up (cumulative incidence: 2, 10, 19, and 34% at 1, 2, 5, and 10 years, respectively). In addition, 53% of people with splanchnic RT were asymptomatic. No clinical or biochemical parameters predicted overall-RT. However, in the 48 people with an additional comprehensive thrombophilic study, factor VIII ≥150% was the only independent factor predicting overall-RT (hazard ratio 7.10, 95% CI 2.17-23.17, p <0.01). In the validation cohort, 19 individuals (27%) presented overall-RT, and it was also independently predicted by factor VIII >150% (hazard ratio 3.71, 95% CI 1.31-10.5, p <0.01). The predictive value of factor VIII was confirmed in both people with idiopathic/local factor aetiology associated NC-SVT.

CONCLUSIONS

People with idiopathic/local factor NC-SVT are at risk of overall-RT. Splanchnic RT can be asymptomatic and requires screening for its detection. Values of factor VIII ≥150% may help identify individuals at high risk of overall-RT who could benefit from long-term anticoagulation.

IMPACT AND IMPLICATIONS

People with idiopathic/isolated local factor non-cirrhotic portal vein thrombosis were previously thought to be at minimal risk of re-thrombosis and therefore did not receive scheduled follow-up. The results of this study are of special interest for hepatologists treating people with non-cirrhotic splanchnic thrombosis, as they show a 25% incidence of re-thrombosis and support the close follow-up of people with factor VIII >150% to ensure the early identification of new thrombotic events.

Bioinformatic analysis and preliminary validation of potential therapeutic targets for COVID-19 infection in asthma patients

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 causes coronavirus disease 19 (COVID-19). The number of confirmed cases of COVID-19 is also rapidly increasing worldwide, posing a significant challenge to human safety. Asthma is a risk factor for COVID-19, but the underlying molecular mechanisms of the asthma-COVID-19 interaction remain unclear.

METHODS

We used transcriptome analysis to discover molecular biomarkers common to asthma and COVID-19. Gene Expression Omnibus database RNA-seq datasets (GSE195599 and GSE196822) were used to identify differentially expressed genes (DEGs) in asthma and COVID-19 patients. After intersecting the differentially expressed mRNAs, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed to identify the common pathogenic molecular mechanism. Bioinformatic methods were used to construct protein-protein interaction (PPI) networks and identify key genes from the networks. An online database was used to predict interactions between transcription factors and key genes. The differentially expressed long noncoding RNAs (lncRNAs) in the GSE195599 and GSE196822 datasets were intersected to construct a competing endogenous RNA (ceRNA) regulatory network. Interaction networks were constructed for key genes with RNA-binding proteins (RBPs) and oxidative stress-related proteins. The diagnostic efficacy of key genes in COVID-19 was verified with the GSE171110 dataset. The differential expression of key genes in asthma was verified with the GSE69683 dataset. An asthma cell model was established with interleukins (IL-4, IL-13 and IL-17A) and transfected with siRNA-CXCR1. The role of CXCR1 in asthma development was preliminarily confirmed.

RESULTS

By intersecting the differentially expressed genes for COVID-19 and asthma, 393 common DEGs were obtained. GO and KEGG enrichment analyses of the DEGs showed that they mainly affected inflammation-, cytokine- and immune-related functions and inflammation-related signaling pathways. By analyzing the PPI network, we obtained 10 key genes: TLR4, TLR2, MMP9, EGF, HCK, FCGR2A, SELP, NFKBIA, CXCR1, and SELL. By intersecting the differentially expressed lncRNAs for COVID-19 and asthma, 13 common differentially expressed lncRNAs were obtained. LncRNAs that regulated microRNAs (miRNAs) were mainly concentrated in intercellular signal transduction, apoptosis, immunity and other related functional pathways. The ceRNA network suggested that there were a variety of regulatory miRNAs and lncRNAs upstream of the key genes. The key genes could also bind a variety of RBPs and oxidative stress-related genes. The key genes also had good diagnostic value in the verification set. In the validation set, the expression of key genes was statistically significant in both the COVID-19 group and the asthma group compared with the healthy control group. CXCR1 expression was upregulated in asthma cell models, and interference with CXCR1 expression significantly reduced cell viability.

CONCLUSIONS

Key genes may become diagnostic and predictive biomarkers of outcomes in COVID-19 and asthma. Video Abstract.

Splanchnic Vein Thrombosis in Myeloproliferative Neoplasms: Treatment Considerations and Unmet Needs

Patients who develop splanchnic vein thrombosis (SVT) in the setting of a myeloproliferative neoplasm (MPN) are at risk for complications including portal hypertension, bleeding, thrombosis, and death. Prompt multidisciplinary treatment is thus necessary to prevent long-term sequelae. However, optimal management strategies are not well established due to a paucity of data. In this review, we very briefly discuss the epidemiology, pathophysiology, and prognosis of MPN-SVT and then more comprehensively explore treatment considerations of MPN-SVT, including anticoagulation, endovascular/surgical intervention, and cytoreductive therapy. We will also highlight current gaps in our knowledge of MPN-SVT and conclude by suggesting future directions to optimize the treatment of MPN-SVT and improve outcomes.

Primary Myelofibrosis in the Prefibrotic Stage Presenting as Portal, Splenic, and Superior Mesenteric Vein Thrombosis: A Case Report and Review of the Literature

INTRODUCTION

Myeloproliferative neoplasms are the most common cause of splanchnic vein thrombosis in the absence of cirrhosis or nearby malignancy.

CASE PRESENTATION

A 31-year-old male presented to the emergency department with epigastric pain associated with mild thrombocytosis and elevated levels of aminotransferases, lactate dehydrogenase, and C-reactive protein. Contrast-enhanced abdominal computed tomography revealed splanchnic venous thrombosis that involved the portal, splenic, and superior mesenteric veins, without signs of chronic liver disease. Anticoagulation with warfarin was immediately started. Diagnostic work-up was remarkable for the presence of the JAK2 V617T mutation and hypercellular bone marrow, with increased myeloid cells and atypical megakaryocytes, consistent with primary myelofibrosis in a prefibrotic stage. No other hypercoagulable conditions were identified.

DISCUSSION

We present a rare case of primary myelofibrosis in the prefibrotic stage presenting as portal-splenic-superior mesenteric vein thrombosis. This demonstrates that extensive splanchnic vein thrombosis may be the onset manifestation of myeloproliferative neoplasms, even in early stages and in the absence of concomitant hypercoagulable conditions. The presence of the JAK2 mutation is an important prothrombotic risk factor that can, per se, contribute to large venous thrombosis.

Clots in unusual places: lots of stress, limited data, critical decisions

Although much less common than deep vein thrombosis of the lower extremities or lungs, clots in unusual locations, including the splanchnic, cerebral, retinal, upper-extremity, and renal locations, present with significant morbidity and mortality. In the last 2 decades, treatment of clots in these unusual locations is primarily managed medically, with interventional and surgical approaches reserved for more severe or refractory cases. The hematologist is well positioned to provide consultation to organ-specific specialties (ie, neurosurgery, hepatology, ophthalmology), especially because acquired and congenital hypercoagulability plays a major role, and anticoagulation is often the primary treatment. Historically, treatment has been based on expert opinion, but systematic reviews and meta-analyses have recently been published. Various societies have produced guidelines for the treatment of clots in unusual locations; however, randomized clinical trial data remain scarce. In the last few years, increasing data have emerged concerning the efficacy of the direct oral anticoagulants in treating clots in unusual locations. Cases have recently been described highlighting atypical thrombosis associated with COVID-19 infection as well as with the ChAdOx1 nCoV-19 (AstraZeneca) vaccine and Johnson and Johnson's Janssen Ad26.COV2.S vaccine. This article reviews clots in unusual locations with an emphasis on the splanchnic (mesenteric, portal, splenic, hepatic) and cerebral circulation. Through a case-based approach, key questions are posed, and data are presented to help guide diagnosis and treatment.

Portal Thrombosis in Cirrhosis: Role of Thrombophilic Disorders

In patients with liver cirrhosis the contribution of inherited and acquired prothrombotic disorders in the development of non-malignant portal vein thrombosis (PVT) is inconclusive. The purpose of this retrospective study was to examine the prevalence of thrombophilia in this setting at our center from January 2012 to November 2019. Tests included gene mutational analysis for Factor V Leiden, prothrombin G20210A, JAK2 (V617F), Calreticulin (CARL), in addition to activated protein C resistance, antithrombin III, protein C and S levels, and antiphospholipid antibodies. We included 77 patients, six of whom (7.8%) had a thrombophilic disorder: antiphospholipid syndrome in four patients, prothrombin gene mutation in one and factor V Leiden mutation in one. This latter patient had also been diagnosed with polycythemia vera years before PVT development. Complete thrombosis of the main portal vein and re-thrombosis after stopping anticoagulation were more frequent in patients with thrombophilia, but the rates of recanalization under anticoagulant therapy were similar among groups. No other difference was accounted between groups. The low prevalence of acquired and inherited thrombophilia found in patients with cirrhosis and PVT support testing for these disorders on an individual basis and avoiding universal screening to reduce costs and unwarranted testing.