Sirolimus for vascular anomalies associated with PTEN hamartoma tumor syndrome.

Phosphatase and tensin homolog (PTEN) hamartoma tumor syndrome (PHTS) is a rare condition associated with vascular anomalies and increased tumor risk. Sirolimus, an mTOR inhibitor used for managing vascular anomalies is underexplored in PHTS. A single-institution retrospective review of children with PHTS and vascular anomalies treated with sirolimus identified seven patients. Median age at sirolimus initiation was 10 years. After a median 2.5-year follow-up, six of seven patients (86%) showed significant clinical improvement. No significant adverse effects were observed, except mild buccal ulcers and acne. This study supports sirolimus as an effective and safe treatment for vascular anomalies in a small group of children with PHTS.

Extraskeletal Ewing Sarcoma Disguised as a Vascular Malformation.

Extraskeletal Ewing sarcoma (EES) is a rare entity, accounting for only 3% of lesions encountered in upper extremity. We present two paediatric patients, who were initially diagnosed with a vascular malformation based on clinical assessment and imaging. Final histopathology revealed Ewing sarcoma of soft tissue origin, confirmed by immunohistochemical analysis. Hand surgeons, who are routinely approached for a myriad of hand pathologies, should be wary and consider EES as a differential when treating such lesions. A multidisciplinary approach with an appropriate treatment algorithm can help in a speedy diagnosis, improving the long-term prognosis of the disease. Level of Evidence: Level V (Therapeutic).

A Peculiar Finding on the Ventrolateral Surface of the Tongue.

Phleboliths are reported as calcifications that occur in vascular malformations, associated with changes in blood flow dynamics, thrombus formation and subsequent calcifications. Radiological examination, such as cone beam computed tomography (CBCT) could help in demonstrating the presence of a calcifiied mass. A 45-year-old male was referred to our service with an asymptomatic nodular purplish lesion located on the ventrolateral tongue. Within the lesion, a stony mass was also evident on palpation. A digital dental radiograph demonstrated two circumscribed radiopaque structures. Phleboliths associated with vascular malformation was the main diagnostic hypothesis. The patient underwent a sclerotherapy protocol allowing surgical accessibility to the area. Phlebolyts were surgically removed using electrocoagulation. Histopathological examination revealed phleboliths in the context of a vascular malformation with intense fibrosis.

Targeted therapy for capillary-venous malformations.

Sporadic venous malformations are genetic conditions primarily caused by somatic gain-of-function mutation of PIK3CA or TEK, an endothelial transmembrane receptor signaling through PIK3CA. Venous malformations are associated with pain, bleedings, thrombosis, pulmonary embolism, esthetic deformities and, in severe cases, life-threatening situations. No authorized medical treatment exists for patients with venous malformations. Here, we created a genetic mouse model of PIK3CA-related capillary venous malformations that replicates patient phenotypes. We showed that these malformations only partially signal through AKT proteins. We compared the efficacy of different drugs, including rapamycin, a mTORC1 inhibitor, miransertib, an AKT inhibitor and alpelisib, a PI3Kα inhibitor at improving the lesions seen in the mouse model. We demonstrated the effectiveness of alpelisib in preventing vascular malformations' occurrence, improving the already established ones, and prolonging survival. Considering these findings, we were authorized to treat 25 patients with alpelisib, including 7 children displaying PIK3CA (n = 16) or TEK (n = 9)-related capillary venous malformations resistant to usual therapies including sirolimus, debulking surgical procedures or percutaneous sclerotherapies. We assessed the volume of vascular malformations using magnetic resonance imaging (MRI) for each patient. Alpelisib demonstrated improvement in all 25 patients. Vascular malformations previously considered intractable were reduced and clinical symptoms were attenuated. MRI showed a decrease of 33.4% and 27.8% in the median volume of PIK3CA and TEK malformations respectively, over 6 months on alpelisib. In conclusion, this study supports PI3Kα inhibition as a promising therapeutic strategy in patients with PIK3CA or TEK-related capillary venous malformations.

Assessment of gene-disease associations and recommendations for genetic testing for somatic variants in vascular anomalies by VASCERN-VASCA.

BACKGROUND: Vascular anomalies caused by somatic (postzygotic) variants are clinically and genetically heterogeneous diseases with overlapping or distinct entities. The genetic knowledge in this field is rapidly growing, and genetic testing is now part of the diagnostic workup alongside the clinical, radiological and histopathological data. Nonetheless, access to genetic testing is still limited, and there is significant heterogeneity across the approaches used by the diagnostic laboratories, with direct consequences on test sensitivity and accuracy. The clinical utility of genetic testing is expected to increase progressively with improved theragnostics, which will be based on information about the efficacy and safety of the emerging drugs and future molecules. The aim of this study was to make recommendations for optimising and guiding the diagnostic genetic testing for somatic variants in patients with vascular malformations. RESULTS: Physicians and lab specialists from 11 multidisciplinary European centres for vascular anomalies reviewed the genes identified to date as being involved in non-hereditary vascular malformations, evaluated gene-disease associations, and made recommendations about the technical aspects for identification of low-level mosaicism and variant interpretation. A core list of 24 genes were selected based on the current practices in the participating laboratories, the ISSVA classification and the literature. In total 45 gene-phenotype associations were evaluated: 16 were considered definitive, 16 strong, 3 moderate, 7 limited and 3 with no evidence. CONCLUSIONS: This work provides a detailed evidence-based view of the gene-disease associations in the field of vascular malformations caused by somatic variants. Knowing both the gene-phenotype relationships and the strength of the associations greatly help laboratories in data interpretation and eventually in the clinical diagnosis. This study reflects the state of knowledge as of mid-2023 and will be regularly updated on the VASCERN-VASCA website (VASCERN-VASCA, https://vascern.eu/groupe/vascular-anomalies/ ).

Correlation between the miR-618 rs2682818 C>A polymorphism and venous malformation susceptibility.

Venous malformations are the most common congenital vascular malformations, and the incidence rate is high. Previous studies have confirmed that a variety of polymorphisms within the miRNA functional region are associated with tumor susceptibility. We examined the correlation between miR-618 rs2682818 C>A and risk of developing venous malformation in a southern Chinese population (1113 patients and 1158 controls). TaqMan genotyping of miR-618 rs2682818 C>A was conducted utilizing real-time fluorescent quantitative PCR. The miR-618 rs2682818 polymorphism was not correlated with susceptibility to venous malformation (CA/AA vs. CC: adjusted odds ratio [AOR] = 1.00, 95% confidence interval [CI] = 0.81-1.25, p = 0.994; AA vs. CC/CA: AOR = 1.10, 95% CI = 0.73-1.65, p = 0.646). Stratified analysis of different subtypes of venous malformation revealed that there was no significant difference in the rs2682818 C>A polymorphism genotypes across these subtypes. Our results indicate that miR-618 rs2682818 C>A polymorphism is not correlated with the susceptibility to venous malformation.

Human iPSC and CRISPR targeted gene knock-in strategy for studying the somatic TIE2L914F mutation in endothelial cells.

Induced pluripotent stem cell (iPSC) derived endothelial cells (iECs) have emerged as a promising tool for studying vascular biology and providing a platform for modelling various vascular diseases, including those with genetic origins. Currently, primary ECs are the main source for disease modelling in this field. However, they are difficult to edit and have a limited lifespan. To study the effects of targeted mutations on an endogenous level, we generated and characterized an iPSC derived model for venous malformations (VMs). CRISPR-Cas9 technology was used to generate a novel human iPSC line with an amino acid substitution L914F in the TIE2 receptor, known to cause VMs. This enabled us to study the differential effects of VM causative mutations in iECs in multiple in vitro models and assess their ability to form vessels in vivo. The analysis of TIE2 expression levels in TIE2L914F iECs showed a significantly lower expression of TIE2 on mRNA and protein level, which has not been observed before due to a lack of models with endogenous edited TIE2L914F and sparse patient data. Interestingly, the TIE2 pathway was still significantly upregulated and TIE2 showed high levels of phosphorylation. TIE2L914F iECs exhibited dysregulated angiogenesis markers and upregulated migration capability, while proliferation was not affected. Under shear stress TIE2L914F iECs showed reduced alignment in the flow direction and a larger cell area than TIE2WT iECs. In summary, we developed a novel TIE2L914F iPSC-derived iEC model and characterized it in multiple in vitro models. The model can be used in future work for drug screening for novel treatments for VMs.

Shear stress and pathophysiological PI3K involvement in vascular malformations.

Molecular characterization of vascular anomalies has revealed that affected endothelial cells (ECs) harbor gain-of-function (GOF) mutations in the gene encoding the catalytic α subunit of PI3Kα (PIK3CA). These PIK3CA mutations are known to cause solid cancers when occurring in other tissues. PIK3CA-related vascular anomalies, or "PIKopathies," range from simple, i.e., restricted to a particular form of malformation, to complex, i.e., presenting with a range of hyperplasia phenotypes, including the PIK3CA-related overgrowth spectrum. Interestingly, development of PIKopathies is affected by fluid shear stress (FSS), a physiological stimulus caused by blood or lymph flow. These findings implicate PI3K in mediating physiological EC responses to FSS conditions characteristic of lymphatic and capillary vessel beds. Consistent with this hypothesis, increased PI3K signaling also contributes to cerebral cavernous malformations, a vascular disorder that affects low-perfused brain venous capillaries. Because the GOF activity of PI3K and its signaling partners are excellent drug targets, understanding PIK3CA's role in the development of vascular anomalies may inform therapeutic strategies to normalize EC responses in the diseased state. This Review focuses on PIK3CA's role in mediating EC responses to FSS and discusses current understanding of PIK3CA dysregulation in a range of vascular anomalies that particularly affect low-perfused regions of the vasculature. We also discuss recent surprising findings linking increased PI3K signaling to fast-flow arteriovenous malformations in hereditary hemorrhagic telangiectasias.

Infantile Hemangiomas and Vascular Anomalies.

Vascular anomalies represent a diverse group of disorders of abnormal vascular development or proliferation. Vascular anomalies are classified as vascular tumors and vascular malformations. Significant advances have been made in the understanding of the pathogenesis, natural history, and genetics of vascular anomalies, allowing for improvements in management including targeted molecular therapies. Infantile hemangiomas are the most common vascular tumor of childhood and follow a distinct natural history of proliferation and involution. Although benign, infantile hemangiomas can be associated with important complications. The use of beta-blockers has revolutionized the management of infantile hemangiomas. Other vascular tumors include pyogenic granulomas, congenital hemangiomas, and kaposiform hemangioendotheliomas, among others. Vascular malformations are categorized based on the type of involved vessel, including capillary malformations, venous malformations, lymphatic malformations, arteriovenous malformations, and mixed vascular malformations. Expert multidisciplinary management of vascular anomalies is critical to optimize outcomes in these patients. [Pediatr Ann. 2024;53(4):e129-e137.].

Biological identity of orbital cavernous venous malformations.

Vascular anomalies comprise a wide spectrum of clinical manifestations related to disturbances in the blood or lymph vessels. They correspond to mainly tumors (especially hemangiomas), characterized by high mitotic activity and proliferation of the vascular endothelium, and malformations, endowed with normal mitotic activity and no hypercellularity or changes in the rate of cell turnover. However, the classifications of these lesions go beyond this dichotomy and consist various systems adapted for and by different clinical subgroups. Thus, the classifications have not reached a consensus and have historically caused confusion regarding the nomenclatures and definitions. Cavernous venous malformations of the orbit, previously called cavernous hemangiomas, are the most common benign vascular orbital lesions in adults. Herein, we have compiled and discussed the various evidences, including clinical, radiological, morphological, and molecular evidence that indicate the non-neoplastic nature of these lesions.

Somatic Loss-of-Function PIK3R1 and Activating Non-hotspot PIK3CA Mutations Associated with Capillary Malformation with Dilated Veins (CMDV).

Common capillary malformations are red vascular skin lesions, most commonly associated with somatic activating GNAQ or GNA11 mutations. We focused on capillary malformations lacking such a mutation to identify previously unreported genetic causes. We used targeted next-generation sequencing on 82 lesions. Bioinformatic analysis allowed the identification of 9 somatic pathogenic variants in PIK3R1 and PIK3CA, encoding for the regulatory and catalytic subunits of phosphoinositide 3-kinase, respectively. Recharacterization of these lesions unraveled a common phenotype: a pale capillary malformation associated with visible dilated veins. Primary endothelial cells from 2 PIK3R1-mutated lesions were isolated, and PI3k-Akt-mTOR and RAS-RAF-MAPK signaling were assessed by western blot. This unveiled an abnormal increase in Akt phosphorylation, effectively reduced by PI3K pathway inhibitors, such as mTOR, Akt, and PIK3CA inhibitors. The effects of mutant PIK3R1 were further studied using zebrafish embryos. Endothelium-specific expression of PIK3R1 mutants resulted in abnormal development of the posterior capillary-venous plexus. In summary, capillary malformation associated with visible dilated veins emerges as a clinical entity associated with somatic pathogenic variants in PIK3R1 or PIK3CA (nonhotspot). Our findings suggest that the activated Akt signaling can be effectively reversed by PI3K pathway inhibitors. In addition, the proposed zebrafish model holds promise as a valuable tool for future drug screening aimed at developing patient-tailored treatments.

Giant congenital fibroblastic connective tissue nevus associated with vascular anomalies.

We described an unusual combination of fibroblastic connective nevus (FCTN) already present at birth with underlying vascular anomalies. Overall, the lesion appeared as a large purplish-brown mass in the groin region up to the third of the right thigh, with partial spontaneous regression during the first three months of life. The FCTN observed exhibited several unusual characteristics: it was congenital, large in size, and located in the lower limbs. Finally, it represented the first case described in which an FCTN arose in association with vascular anomalies.

Epilepsy with faint capillary malformation or reticulated telangiectasia associated with mosaic AKT3 pathogenic variants.

Capillary malformations (CMs) are the most common type of vascular anomalies, affecting around 0.3% of newborns. They are usually caused by somatic pathogenic variants in GNAQ or GNA11. PIK3CA and PIK3R1, part of the phosphoinositide 3-kinase-protein kinase B-mammalian target of rapamycin pathway, are mutated in fainter CMs such as diffuse CM with overgrowth and megalencephaly CM. In this study, we present two young patients with a CM-like phenotype associated with cerebral anomalies and severe epilepsy. Pathogenic variants in PIK3CA and PIK3R1, as well as GNAQ and GNA11, were absent in affected cutaneous tissue biopsies. Instead, we identified two somatic pathogenic variants in the AKT3 gene. Subsequent analysis of the DNA obtained from surgically resected brain tissue of one of the two patients confirmed the presence of the AKT3 variant. Focal cortical dysplasia was also detected in this patient. Genetic analysis thus facilitated workup to reach a precise diagnosis for these patients, associating the vascular anomaly with the neurological symptoms. This study underscores the importance of searching for additional signs and symptoms to guide the diagnostic workup, especially in cases with atypical vascular malformations. In addition, it strongly emphasizes the significance of genotype-phenotype correlation studies in guiding clinicians' informed decision-making regarding patient care.

Comprehensive phenotypic and genomic characterization of venous malformations.

Venous malformations (VMs) are the most common vascular malformations. TEK and PIK3CA are the causal genes of VMs, and may be involved in the PI3K/AKT pathway. However, the downstream mechanisms underlying the TEK or PIK3CA mutations in VMs are not completely understood. This study aimed to identify a possible association between genetic mutations and clinicopathological features. A retrospective clinical, pathological, and genetic study of 114 patients with VMs was performed. TEK, PIK3CA, and combined TEK/PIK3CA mutations were identified in 49 (43%), 13 (11.4%), and 2 (1.75%) patients, respectively. TEK-mutant VMs more commonly occurred in younger patients than TEK and PIK3CA mutation-negative VMs (other-mutant VMs), and showed more frequent skin involvement and no lymphocytic aggregates. No significant differences were observed in sex, location of occurrence, malformed vessel size, vessel density, or thickness of the vascular smooth muscle among the VM genotypes. Immunohistochemical analysis revealed that the expression levels of phosphorylated AKT (p-AKT) were higher in the TEK-mutant VMs than those in PIK3CA-mutant and other-mutant VMs. The expression levels of p-mTOR and its downstream effectors were higher in all the VM genotypes than those in normal vessels. Spatial transcriptomics revealed that the genes involved in "blood vessel development", "positive regulation of cell migration", and "extracellular matrix organization" were up-regulated in a TEK-mutant VM. Significant genotype-phenotype correlations in clinical and pathological features were observed among the VM genotypes, indicating gene-specific effects. Detailed analysis of gene-specific effects in VMs may offer insights into the underlying molecular pathways and implications for targeted therapies.

Progressive vascular tumor in infant: A case report and literature review of PIK3CA vascular malformation.

PURPOSE: Vascular anomalies are classified as either vascular tumors or vascular malformations. Vascular malformations can be difficult to diagnose and treat in the pediatric population and can masquerade as malignant processes. Understanding the genetics behind vascular malformations can lead to identification of specific mutations which can be treated with targeted immunotherapy. METHODS: Our case presents a pediatric patient with progressively enlarging vascular malformation despite multiple surgical resections and systemic medical treatments who underwent genetic evaluation and was found to have PIK3CA mutation. RESULTS: After identification of PIK3CA mutation, our patient was successfully treated with the p110ɑ-specific inhibitor, alpelisib, with both shrinkage of malformation on follow-up imaging as well as gains in her developmental milestones. CONCLUSION: Progressive vascular malformations in the pediatric population can be hard to diagnose and treat and are thought to arise from somatic mutations. Our case highlights a patient with progressive malformation despite multiple surgical resections who was successfully treated with targeted immunotherapy after proper identification of genetic mutation.