TIE2 gain-of-function mutation in a patient with pancreatic lymphangioma associated with blue rubber-bleb nevus syndrome: report of a case

Clinical characteristics of blue rubber bleb nevus syndrome in adults: systematic scoping review

BACKGROUND

Blue rubber bleb nevus syndrome (BRBNS) is a rare systemic vascular anomaly mainly affecting the skin, central nervous system and gastrointestinal tracts. Its clinical presentation and characteristics in adult patients are unclear.

AIM

To clarify the characteristics of BRBNS in adult patients with a focus on gastrointestinal symptoms.

METHODS

Following the PRISMA Extension for Scoping Reviews, we searched MEDLINE and EMBASE for all peer-reviewed articles using keywords including 'Blue rubber bleb nevus syndrome' from their inception to 28 December 2021.

RESULTS

Ninety-nine articles, including 3 observational studies and 101 cases from case reports and series, were included. Observational studies were consistently with small sample sizes, and there was only one prospective study to show the effectiveness of sirolimus in BRBNS. Common clinical presentations included anemia (50.5%) and melena (26.5%). While skin findings were known to be representative of BRBNS, only 57.4% had known vascular malformation. The diagnosis was primarily made clinically, with only 1% being diagnosed with BRBNS through genetic sequencing. Distribution of BRBNS-related lesions were variable, but predominantly oral (55.9%), followed by small bowel (49.5%), colorectal (35.6%) and stomach (26.7%) vascular malformations.

CONCLUSION

While it has been underrecognized, adult BRBNS could be a culprit for refractory microcytic anemia or occult gastrointestinal bleeding. Further studies are critical to establish a uniform understanding of diagnosis and treatment for those with adult BRBNS. The utility of genetic testing in adult BRBNS diagnosis and the patient characteristics that may benefit from sirolimus, a potentially curative agent, remain to be clarified.

Treatment of sirolimus in the pathological femoral fracture related to blue rubber bleb nevus syndrome: A case report

RATIONALE

Blue rubber bleb nevus syndrome (BRBNS) is a rare condition with characteristic vascular malformations of the skin, most frequently lesions of the gastrointestinal tract and central nervous system, and less often, the musculoskeletal system. We report a 5-year case of BRBNS complicated with pathological femoral fracture that was successfully treated with sirolimus.

PATIENT CONCERNS

We report the case of a 1-week-old girl with a diagnosis of BRBNS who had multiple venous malformations over her body. She also presented with right lower-limb swelling and complicated with a pathological femoral fracture.

DIAGNOSES

BRBNS with the complication of pathological femoral fracture.

INTERVENTIONS

Treatment with low-dose sirolimus as an antiangiogenic agent was administered, combined with hip spica protection.

OUTCOMES

The vascular lesion was reduced after about 6 months and the fracture site had healed around 2.5 years after initiation of sirolimus therapy. There were no drug adverse effects at the 5-year follow-up point. The patient showed excellent spirit and no obvious sequelae were found.

LESSONS

To the best of our knowledge, this is the first report of the successful use of sirolimus in a patient with a pathological femoral fracture related to BRBNS complications.

Sirolimus alternative to blood transfusion as a life saver in blue rubber bleb nevus syndrome: A case report

RATIONALE

Blue rubber bleb nevus syndrome (BRBNS) is a rare disease characterized by multiple venous malformations. The gastrointestinal bleeding and secondary iron deficiency anemia are the most common complications. There are currently no effective treatments for BRBNS. Here, we report a case of successful treatment with a small dose of sirolimus of a BRBN patient with a de novo gene mutation.

PATIENT CONCERNS

A 12-year-old female was admitted to our hospital with multiple hemangiomas for 12 years. The patient often displayed melena; she recently received transfusion of 2 units of red blood cells once every 2 weeks. Multiple fist-sized hemangiomas were piled up on both sides and back of the neck, and were also noted on the arms, legs, chest, back, and on the tip of the tongue. The laboratory findings demonstrated severe anemia. Blood sample sequencing detected a heterozygous de novo mutation c.2545C > Tin the TEK gene.

DIAGNOSES

Based on these findings, final diagnosis of Blue rubber bleb nevus syndrome (BRBNS) was made.

INTERVENTIONS

After the diagnosis, low-dose sirolimus was orally administered.

OUTCOMES

The patient's hemoglobin was increased after treatment with sirolimus for 1 month. Since the initial treatment with sirolimus, she had not received any blood transfusions. The skin and mucosal hemangioma decreased significantly, and new digestive tract hemorrhage, muscle hematoma, or adverse drug reactions were not observed.

LESSONS

we report a case of a mutation in exon 15 of the TEK gene leading to BRBN. It was successfully treated with a small dose of sirolimus as an alternative to blood transfusion in order to save the of BRBN patient's life.

The pathobiology of vascular malformations: insights from human and model organism genetics

Vascular malformations may arise in any of the vascular beds present in the human body. These lesions vary in location, type, and clinical severity of the phenotype. In recent years, the genetic basis of several vascular malformations has been elucidated. This review will consider how the identification of the genetic factors contributing to different vascular malformations, with subsequent functional studies in animal models, has provided a better understanding of these factors that maintain vascular integrity in vascular beds, as well as their role in the pathogenesis of vascular malformations. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Enteroscopic sclerotherapy in blue rubber bleb nevus syndrome

Blue rubber bleb nevus syndrome (BRBNS) is a rare syndrome characterized by multiple vascular malformations of varying size and appearance that present predominantly on the skin and within the gastrointestinal tract and, less often, in other internal organs. Gastrointestinal lesions of BRBNS can cause acute or chronic bleeding, and the treatment is challenging. In this case, we reported a successful treatment of vascular malformations in all segments of gastrointestinal tract, including the small intestine, by endoscopic sclerotherapy, in a 10-year-old boy with BRBNS.

Advances in the therapeutic use of mammalian target of rapamycin (mTOR) inhibitors in dermatology

Significant developments in the use of mammalian target of rapamycin (mTOR) inhibitors (mTORIs) as immunosuppressant and antiproliferative agents have been made. Recent advances in the understanding of the mTOR signaling pathway and its downstream effects on tumorigenesis and vascular proliferation have broadened the clinical applications of mTORIs in many challenging disorders such as tuberous sclerosis complex, pachyonychia congenita, complex vascular anomalies, and inflammatory dermatoses. Systemic mTORI therapy has shown benefits in these areas, but is associated with significant side effects that sometimes necessitate drug holidays. To mitigate the side effects of systemic mTORIs for dermatologic applications, preliminary work to assess the potential of percutaneous therapy has been performed, and the evidence suggests that percutaneous delivery of mTORIs may allow for effective long-term therapy while avoiding systemic toxicities. Additional large placebo-controlled, double-blinded, randomized studies are needed to assess the efficacy, safety, duration, and tolerability of topical treatments. The objective of this review is to provide updated information on the novel use of mTORIs in the management of many cutaneous disorders.

Endoscopic management of blue rubber bleb nevus syndrome: A case report

Blue rubber bleb nevus syndrome (BRBNS) is a rare disorder characterized by multiple recurrent vascular malformations, including hemangioma, which primarily locate on the skin and gastrointestinal (GI) tract. The present study reports a 22-year-old female with iron-deficiency anemia and recurrent episodes of melena. The patient also exhibited characteristic venous malformations of the skin. Endoscopy revealed several hemangiomas in the GI tract. The hemangiomas were treated by ligation using a nylon cord, while small blue mucosal polypoid lesions were treated using a sclerosing agent during colonoscopy and double-balloon enteroscopy. The patient was reviewed regularly for three years following surgery and no further bleeding episodes were noted.

Venous malformation-causative TIE2 mutations mediate an AKT-dependent decrease in PDGFB

Mutations in the endothelial cell (EC) tyrosine kinase receptor TIE2 cause inherited and sporadic forms of venous malformation. The recurrent somatic mutation L914F and common germline mutation R849W differ in terms of phosphorylation level, as well as sub-cellular localization and trafficking of the receptor. Previous studies have shed light on certain pathogenic properties of R849W, but the mechanisms of action of L914F are unknown. We used global gene expression profiling to study the effects of L914F on ECs. We found that L914F strongly dysregulates genes involved in vascular development, cell migration and extracellular matrix processing, while R849W has weak effects. We also demonstrate, for the first time, that TIE2-mutant ECs are deficient in the production of PDGFB, both in vitro and ex vivo in patient tissues. This defect is mediated by the chronic, ligand-independent activation of AKT by the mutant receptors. Inadequate secretion of the major mural cell attractant likely plays an important role in the development of abnormal vascular channels, contributing to the characteristic paucity of surrounding vascular smooth muscle cells.

Vascular anomalies: from genetics toward models for therapeutic trials

Vascular anomalies are localized abnormalities that occur during vascular development. Several causative genes have been identified not only for inherited but also for some sporadic forms, and the molecular pathways involved are becoming understood. This gives us the opportunity to generate animals carrying the causative genetic defects, which we hope model the phenotype seen in human patients. These models would enable us not only to test known antiangiogenic drugs, but also to develop novel approaches for treatment, directly targeting the mutated protein or molecules implicated in the pathophysiological signaling pathways.

[Haplotype analysis for mucocutaneous venous malformations in a Chinese Han ethnic family]

A Chinese Han ethnic family with mucocutaneous venous malformations (VMCM) was investigated. This family has autosomal dominantly inherited VMCM in five generations, and the offspring has a 50% risk of this inherited disorder. Affected individuals have small, spongy, and multiple vascular lesions, which often locate in the skin, oral mucosa, and upper and lower extremities. None of the family members had gastrointestinal bleeding, central nervous system involvement and cardiac defects. Pathological analysis showed that the veins have irregular vascular space and walls with variable thickness. All phenotypes of the patients displayed the basic characters of VMCM. To analyze the genetic locus and haplotype, genomic DNA of 26 family members was obtained from peripheral leukocytes, and the linkage analysis and haplotypes analysis were performed using microsatellites markers. The results of two-point linkage analysis and haplotype analysis showed that the disease-causing gene located within a 7 cM region between D9S1121 and D9S161 on the short arm of chromosome 9. The study firstly reported the Chinese family with VMCM, which disease-causing gene is located in 9p, consistent with western VMCM families reported. Four flanking markers, D9S1121, D9S169, D9S16 and D9S248, were used to define the linkage haplotypes in the family, which can provide useful informaion for researchers to study VMCM in different racial background.

Blue rubber bleb nevus syndrome: imaging of small bowel lesions with peroral CT enterography

Blue rubber bleb nevus syndrome (BRBNS) is a rare entity that consists of multiple venous malformations involving several organ systems, particularly the skin and the gastrointestinal tract. The diagnosis is based on clinical findings; however, imaging is required to investigate the extent of involvement and complications. A 17-year-old patient, with multiple blue skin nevus, was admitted to the emergency room of our hospital with severe gastrointestinal bleeding and melena. Upper endoscopy showed two wine-color vascular lesions in the duodenum, and colonoscopy revealed multiple lesions in the colon. Peroral CT enterography demonstrated multiple (more than 30) contrast-enhanced polypoid small bowel lesions, ranging in size from 5 to 16 mm. Some lesions contained millimetric calcifications representing phleboliths. The patient also had three pancreatic lesions which showed homogenous enhancement on the delayed images. Our findings show that peroral CT enterography is useful to demonstrate the extent of small bowel lesions of BRBNS. This is the first report of pancreatic involvement of BRBNS.

Cystic lymphangioma of the pancreas with spontaneous rupture: report of a case

Lymphangioma is a benign and congenital malformation of the lymphatic system. Most lymphangiomas are preferentially located in the head and neck region. The abdominal organs are uncommon sites of origin. Several cases of lymphangioma in abdominal organs were reported, however, the pancreas is one of the rarest origins. Generally, intra-abdominal lymphangioma is asymptomatic and found incidentally, but in some cases, the patient complains of abdominal distension or a palpable mass. We describe the case of a 38-year-old male who presented with sudden-onset upper abdominal pain. Rupture of a cystic tumor of the pancreatic head was suspected, based on the findings of computed tomography, magnetic resonance imaging and endoscopic ultrasonography. Subtotal stomach-preserving pancreaticoduodenectomy was undertaken. The tumor, which was 4 × 4.5 × 8 cm in size, was pathologically diagnosed as a cystic lymphangioma. In conclusion, pancreatic lymphangioma is mostly asymptomatic, a ruptured case causing ‘acute abdomen’ has never been reported. Since lymphangioma is benign, it could be observed with accurate diagnosis. The surgical indication would be limited to cases of symptomatic lymphangiomas.

Cervical cystic lymphangioma in a patient with blue rubber bleb nevus syndrome: clinical case report and review of the literature

We present the case of a 9-year-old boy diagnosed with blue rubber bleb nevus syndrome, who showed a very large left cervical cystic lymphangioma. He was previously subjected to various treatments for lesions in the intestinal tract including blood transfusions for anemia, sclerosis, enterotomies or resections. The tumor was resected without any complications and the anatomopathologic report confirmed this diagnosis. The blue cavernous hemangioma syndrome (or blue rubber bleb nevus syndrome) is a rare disease characterized by cavernous angiomas involving the skin and gastrointestinal tract. Several cases of cystic lymphangiomas associated with this syndrome have been published recently and lymphomatous differentiation has been identified in the cells of cutaneous lesions. Given their common embryological origin, we underscore the importance of bearing in mind that it is possible for different types of vascular malformations to coexist in the same patient.

Cystic lymphangioma of the pancreas with congenital intrahepatic duct dilatation and choledochal cyst

Cystic lymphangioma of the pancreas is an extremely rare benign tumor of lymphatic origin. We report on a 68-year-old woman who had experienced epigastric abdominal distension and nausea for over 1 year. Sonography revealed a cystic-solid mixed mass in the head of pancreas, with intrahepatic and extrahepatic duct dilatation. A diagnosis of cystic lymphangioma with congenital intrahepatic duct dilatation and choledochal cyst was made after excision and pathologic examination. Preoperative diagnosis of cystic lymphangioma of the pancreas is difficult, and carefulsonographic evaluation is required.

Elevated expression of c-kit in small venous malformations of blue rubber bleb nevus syndrome

The blue rubber bleb nevus syndrome (BRBNS, syn. bean syndrome) is a rare disease characterized by multiple cutaneous and gastrointestinal venous malformations associated with severe bleeding. However, the underlying molecular mechanisms are unknown and no targeted therapeutic approach exists to date. Here we report the case of a 19-year-old male patient with severe BRBNS in whom we analyzed the expression of tyrosine kinases frequently involved in tumor development by immunohistochemistry (vascular endothelial growth factor receptor-2, stem cell growth factor receptor (c-kit), platelet-derived growth factor receptor-β, and stem cell tyrosine kinase-1). A prominent expression of c-kit was detectable in smaller blood vessels, which also showed a moderate expression of the proliferation marker MIB1. Surprisingly, other growth factor receptors stained negatively. We therefore conclude that pharmacological inhibition of the c-kit signaling pathway in cavernous hemangiomas by selective kinase inhibitors may offer options in the treatment of BRBNS patients.

Hereditary cutaneomucosal venous malformations are caused by TIE2 mutations with widely variable hyper-phosphorylating effects

Mutations in the angiopoietin receptor TIE2/TEK have been identified as the cause for autosomal dominantly inherited cutaneomucosal venous malformation (VMCM). Thus far, two specific germline substitutions (R849W and Y897S), located in the kinase domain of TIE2, have been reported in five families. The mutations result in a fourfold increase in ligand-independent phosphorylation of the receptor. Here, we report 12 new families with TEK mutations. Although the phenotype is primarily characterized by small multifocal cutaneous vascular malformations, many affected members also have mucosal lesions. In addition, cardiac malformations are observed in some families. Six of the identified mutations are new, with three located in the tyrosine kinase domain, two in the kinase insert domain, and another in the carboxy terminal tail. The remaining six are R849W substitutions. Overexpression of the new mutants resulted in ligand-independent hyperphosphorylation of the receptor, suggesting this is a general feature of VMCM-causative TIE2 mutations. Moreover, variation in the level of activation demonstrates, to the best of our knowledge for the first time, that widely differing levels of chronic TIE2 hyperphosphorylation are tolerated in the heterozygous state, and are compatible with normal endothelial cell function except in the context of highly localized areas of lesion pathogenesis.

Somatic mutations in angiopoietin receptor gene TEK cause solitary and multiple sporadic venous malformations

Germline substitutions in the endothelial cell tyrosine kinase receptor TIE2 (encoded by TEK) cause a rare, inherited form of venous anomaly known as a mucocutaneous venous malformation (VMCM; refs. 1, 2, 3 and V.W., N.L., M.U., A. Irrthum, L.M.B. et al., unpublished data). We identified a somatic 'second hit' causing loss of function of TIE2 in a resected VMCM and assessed whether such localized, tissue-specific events have a role in the etiology of sporadic venous malformations, which are far more common. We identified eight somatic TEK mutations in lesions from 28 of 57 individuals (49.1%) with sporadic venous malformations; the mutations were absent from the individuals' blood and control tissues. The somatic mutations included one causing a frequent L914F substitution and several double mutations in cis, all of which resulted in ligand-independent TIE2 hyperphosphorylation in vitro. When overexpressed in human umbilical vein endothelial cells, the L914F mutant was abnormally localized and responded to ligand, in contrast to wild-type TIE2 and the common, inherited R849W mutant, suggesting that the mutations have distinct effects. The presence of the same mutations in multifocal sporadic venous malformations in two individuals suggests a common origin for the abnormal endothelial cells at the distant sites. These data show that a sporadic disease may be explained by somatic changes in a gene causing rare, inherited forms and pinpoint TIE2 pathways as potential therapeutic targets for venous malformations.

Proliferating mesodermal cells in murine embryos exhibiting macrophage and lymphendothelial characteristics

BACKGROUND

The data on the embryonic origin of lymphatic endothelial cells (LECs) from either deep embryonic veins or mesenchymal (or circulating) lymphangioblasts presently available remain inconsistent. In various vertebrates, markers for LECs are first expressed in specific segments of embryonic veins arguing for a venous origin of lymph vessels. Very recently, studies on the mouse have strongly supported this view. However, in the chick, we have observed a dual origin of LECs from veins and from mesodermal lymphangioblasts. Additionally, in murine embryos we have detected mesenchymal cells that co-express LEC markers and the pan-leukocyte marker CD45. Here, we have characterized the mesoderm of murine embryos with LEC markers Prox1, Lyve-1 and LA102 in combination with macrophage markers CD11b and F4/80.

RESULTS

We observed cells co-expressing both types of markers (e.g. Prox1 - Lyve-1 - F4/80 triple-positive) located in the mesoderm, immediately adjacent to, and within lymph vessels. Our proliferation studies with Ki-67 antibodies showed high proliferative capacities of both the Lyve-1-positive LECs of lymph sacs/lymphatic sprouts and the Lyve-1-positive mesenchymal cells.

CONCLUSION

Our data argue for a dual origin of LECs in the mouse, although the primary source of embryonic LECs may reside in specific embryonic veins and mesenchymal lymphangioblasts integrated secondarily into lymph vessels. The impact of a dual source of LECs for ontogenetic, phylogenetic and pathological lymphangiogenesis is discussed.

[Pathogenesis and genetics of vascular anomalies]

Vascular anomalies, divided into vascular tumors and vascular malformations, are localized defects of angiogenesis. Hemangiomas appear soon after birth, grow quickly, and then spontaneously, but slowly, disappear. In contrast, vascular malformations are congenital defects of vascular development that grow proportionately with the child. Most vascular anomalies are considered non-hereditary. However, due to detailed analysis inherited forms have been observed, which has led to identify mutations in three genes causing familial vascular malformations: in the angiopoietin receptor TIE2 in mucocutaneous venous malformations (VMCM), in glomulin in glomuvenous malformations (GVM) and in RASA1 in the newly recognized phenotype capillary malformation-arteriovenous malformation (CM-AVM). Identification of the causative genes has permitted more precise diagnosis and differential diagnosis, evaluation of phenotypic variability among patients with a proven mutation, study of used treatments in more homogeneous patient groups, and elucidation of the etiopathogenic mechanisms behind vascular malformations. Further studies are needed to unravel the role of genetic variations in the various vascular malformations and to unravel the precise molecular mechanisms that lead to development of these vascular lesions. This should provide development of new-targeted therapies.