The role of key biomarkers in lymphatic malformation: An updated review

The lymphatic system, crucial for tissue fluid balance and immune surveillance, can be severely impacted by disorders that hinder its activities. Lymphatic malformations (LMs) are caused by fluid accumulation in tissues owing to defects in lymphatic channel formation, the obstruction of lymphatic vessels or injury to lymphatic tissues. Somatic mutations, varying in symptoms based on lesions' location and size, provide insights into their molecular pathogenesis by identifying LMs' genetic causes. In this review, we collected the most recent findings about the role of genetic and inflammatory biomarkers in LMs that control the formation of these malformations. A thorough evaluation of the literature from 2000 to the present was conducted using the PubMed and Google Scholar databases. Although it is obvious that the vascular endothelial growth factor receptor 3 mutation accounts for a significant proportion of LM patients, several mutations in other genes thought to be linked to LM have also been discovered. Also, inflammatory mediators like interleukin-6, interleukin-8, tumor necrosis factor-alpha and mammalian target of rapamycin are the most commonly associated biomarkers with LM. Understanding the mutations and genes expression responsible for the abnormalities in lymphatic endothelial cells could lead to novel therapeutic strategies based on molecular pathways.

Lack of embryonic homozygous or adult heterozygous lymphatic phenotypes for a Sos1 mutation and lack of lymphatic embryonic phenotypes for a homozygous Cx47 mutation in mice

We have studied the lymphatic phenotypes of 2 mutations, known to cause abnormalities of lymphatics in humans, in mice. The Cx47 R260C mutation (variably penetrant in humans heterozygous for it and causing limb lymphedema) had an adult mouse phenotype of hyperplasia and increased lymph nodes only in homozygous condition but we did not find any anatomical phenotype in day 16.5 homozygous embryos. Mice harboring the Sos1 mutation E846K (causing Noonan's in man which occasionally shows lymphatic dysplasia) had no adult heterozygous phenotype in lymphatic vessel appearance and drainage (homozygotes are early embryonic lethals) while day 16.5 heterozygous embryos also had no detectable anatomical phenotype.

Non-contrast MR lymphography of rare lymphatic abnormalities

Detailed imaging of the lymphatic system often requires direct injection of contrast into lymph nodes which can be technically challenging, time consuming, and produce painful stimuli. We sought to describe the use of non-contrast MR lymphography (NCMRL) for normal controls and patients with a variety of rare disorders associated with lymphatic pathologies. Two control subjects and five affected patients (decompensated Fontan circulation, central conducting lymphatic abnormality, familial lymphedema and two with Gorham-Stout disease) were studied. NCMRL images were segmented in a semiautomated fashion and the major lymphatic channels and thoracic duct (TD) highlighted for identification. Adequate imaging was available for both controls and 4/5 affected patients; the youngest patient could not be imaged given patient motion. For the two controls, the TD was seen in the expected anatomic location. For the decompensated Fontan patient, there were numerous tortuous lymphatic channels, predominantly in the upper chest and neck. For the familial lymphedema patient, a TD was not identified; instead, peripheral lymphatic collaterals near the lateral chest walls. For the first Gorham- Stout patient, the TD was enlarged with large intrathoracic lymph collections. For the second Gorham-Stout patient, there were bilateral TD with lymph collections in vertebral bodies. Using NCMRL, we were able to image normal and abnormal lymphatic systems. An important learning point is the potential need for sedation for younger patients due to long image acquisition times and fine resolution of the structures of interest.

PIK3CA mutations are specifically localized to lymphatic endothelial cells of lymphatic malformations

Lymphatic malformations (LM) are characterized by the overgrowth of lymphatic vessels during pre- and postnatal development. Macrocystic, microcystic and combined forms of LM are known. The cysts are lined by lymphatic endothelial cells (LECs). Resection and sclerotherapy are the most common treatment methods. Recent studies performed on LM specimens in the United States of America have identified activating mutations in the phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) gene in LM. However, whole tissue but not isolated cell types were studied. Here, we studied LM tissues resected at the University Hospitals Freiburg and Regensburg, Germany. We isolated LECs and fibroblasts separately, and sequenced the commonly affected exons 8, 10, and 21 of the PIK3CA gene. We confirm typical monoallelic mutations in 4 out of 6 LM-derived LEC lines, and describe two new mutations i.) in exon 10 (c.1636C>A; p.Gln546Lys), and ii.) a 3bp in-frame deletion of GAA (Glu109del). LM-derived fibroblasts did not possess such mutations, showing cell-type specificity of the gene defect. High activity of the PIK3CA—AKT- mTOR pathway was demonstrated by hyperphosphorylation of AKT-Ser473 in all LM-derived LECs (including the ones with newly identified mutations), as compared to normal LECs. Additionally, hyperphosphorylation of ERK was seen in all LM-derived LECs, except for the one with Glu109del. In vitro, the small molecule kinase inhibitors Buparlisib/BKM-120, Wortmannin, and Ly294002, (all inhibitors of PIK3CA), CAL-101 (inhibitor of PIK3CD), MK-2206 (AKT inhibitor), Sorafenib (multiple kinases inhibitor), and rapamycin (mTOR inhibitor) significantly blocked proliferation of LM-derived LECs in a concentration-dependent manner, but also blocked proliferation of normal LECs. However, MK-2206 appeared to be more specific for mutated LECs, except in case of Glu109 deletion. In sum, children that are, or will be, treated with kinase inhibitors must be monitored closely.

[Venolymphatic malformation with bone erosion. An unusual affectation in these lesions]

A 30 year old male presented with a cutaneous lesion on the distal area of the 5th toe with involvement of the outer edges. Macroscopically, it was a 1cm violaceous and keratotic lesion. Radiography showed an increase in soft tissue, possibly due to a vascular lesion. MRI showed a hyper-intense signal with erosion of the distal phalanx compatible with a low-flow vascular malformation. The distal phalanx was amputated. Histopathology revealed a lesion formed by venous and D2-40 positive lymphatic vessels. This case highlights the fact that even minimal skin involvement in vascular malformations may conceal an important deeper lesion, such as erosion of the cortical bone.

Somatic NRAS mutation in patient with generalized lymphatic anomaly

Generalized lymphatic anomaly (GLA or lymphangiomatosis) is a rare disease characterized by a diffuse proliferation of lymphatic vessels in skin and internal organs. It often leads to progressive respiratory failure and death, but its etiology is unknown. Here, we isolated lymphangiomatosis endothelial cells from GLA tissue. These cells were characterized by high proliferation and survival rates, but displayed impaired capacities for migration and tube formation. We employed whole exome sequencing to search for disease-causing genes and identified a somatic mutation in NRAS. We used mouse and zebrafish model systems to initially evaluate the role of this mutation in the development of the lymphatic system, and we studied the effect of drugs blocking the downstream effectors, mTOR and ERK, on this disease.

Schimmelpenning Syndrome: An Association with Vascular Anomalies

Objective:

Schimmelpenning syndrome is a rare neurocutaneous disorder characterized by craniofacial nevus sebaceus in association with seizures, developmental delay, and ocular or skeletal pathology. Vascular anomalies also have been described in this condition, and some authors have suggested that the two entities are associated. The purpose of this study was to determine the prevalence of vascular anomalies in Schimmelpenning syndrome.

Methods:

We reviewed the medical records of patients with Schimmelpenning syndrome who were evaluated or were managed at Children's Hospital Boston between 1980 and 2005. In addition, all published cases purported to be Schimmelpenning syndrome were analyzed to determine whether the primary diagnosis was accurate and whether or not there were concurrent vascular anomalies.

Results:

Three of nine patients (33.3%) in our series had a vascular malformation. One patient had coarctation, aortic aneurysm, renal artery, and carotid stenosis; another had a thoracic lymphatic anomaly with chylothorax; and the third had lymphedema of the lower extremities and lymphatic malformation of the neck/chest with chylothorax. Additional findings were seizures (78%), ocular pathology (78%), developmental delay (56%), and skeletal abnormalities (67%). Of 119 cases of authenticated Schimmelpenning syndrome in the literature, 18 vascular malformations were documented in 15 patients (12.6%): venous (n = 7); arterial (n = 5); lymphatic (n = 3); capillary (n = 2); and arteriovenous (n = 1).

Conclusions:

Vascular malformations occur with a higher frequency (12.6 to 33%) in patients with Schimmelpenning syndrome compared with the general population (<1%). Therefore, we conclude that there is an association between vascular anomalies and Schimmelpenning syndrome.

Anatomical Variations of the Thoracic Duct: A Preliminary Report in Adult and Fetal Specimens

The study aim is to evaluate anatomical variations of the thoracic duct using a specialized sequential injection procedure. The different types, frequencies, and anatomical topography were recorded and evaluated using 12 adult and 16 fetus specimens. By employing a perfusion pump device, cadavers were sequentially perfused with acrylic colored latex first through the internal marginal vein, then the thoracic duct at the interazygous-aortic recess, and finally through the posterior tibial artery. After perfusion, thoracic ducts were identified, partially dissected, and cadavers fixed by soaking in an aqueous solution of 5% formalin (v/v). Finally, further dissection and detailed photography were performed. Plexus shapes at different levels were clearly evident in 80% of the adult specimens. Whereas the presence of the cisterna chyli was detected in 100% of fetuses as an ampule dilatation at the beginning of the thoracic duct, in only one adult specimen was a dilatation found at the lumbar lymphatic trunk level. Functionally it is not known whether these modified anatomical features (plexus shapes) have served to compensate (as a derivative pathway) for lymphatic hypertension in life as a reflection of lymphatic system challenges and subsequent growth in the adult specimens.

CHD4-regulated plasmin activation impacts lymphovenous hemostasis and hepatic vascular integrity

The chromatin-remodeling enzyme CHD4 maintains vascular integrity at mid-gestation; however, it is unknown whether this enzyme contributes to later blood vessel or lymphatic vessel development. Here, we addressed this issue in mice harboring a deletion of Chd4 specifically in cells that express lymphatic vessel endothelial hyaluronan receptor 1 (LYVE1), which include lymphatic endothelial cells (LECs) and liver sinusoidal endothelial cells. Chd4 mutant embryos died before birth and exhibited severe edema, blood-filled lymphatics, and liver hemorrhage. CHD4-deficient embryos developed normal lymphovenous (LV) valves, which regulate the return of lymph to the blood circulation; however, these valves lacked the fibrin-rich thrombi that prevent blood from entering the lymphatic system. Transcripts of the urokinase plasminogen activator receptor (uPAR), which facilitates activation of the fibrin-degrading protease plasmin, were upregulated in Chd4 mutant LYVE1+ cells, and plasmin activity was elevated near the LV valves. Genetic reduction of the uPAR ligand urokinase prevented degradation of fibrin-rich thrombi at the LV valves and largely resolved the blood-filled lymphatics in Chd4 mutants. Urokinase reduction also ameliorated liver hemorrhage and prolonged embryonic survival by reducing plasmin-mediated extracellular matrix degradation around sinusoidal blood vessels. These results highlight the susceptibility of LV thrombi and liver sinusoidal vessels to plasmin-mediated damage and demonstrate the importance of CHD4 in regulating embryonic plasmin activation after mid-gestation.

Combining Foxc2 and Connexin37 deletions in mice leads to severe defects in lymphatic vascular growth and remodeling

Connexins (Cxs), proteins that are vital for intercellular communication in vertebrates, have recently been shown to play a critical role in lymphatic development. However, our knowledge is currently limited regarding the functional relationships of Cxs with other proteins and signaling pathways. Cell culture studies have shown that Cx37 is necessary for coordinated activation of the transcription factor NFATc1, which cooperates with Foxc2 (another transcription factor) during lymphatic endothelial development. These data suggest that Cxs, Foxc2, and NFATc1 are part of a common developmental pathway. Here, we present a detailed characterization of Foxc2(+/-)Cx37(-/-) mice, demonstrating that lymphatic network architecture and valve formation rely on the concurrent embryonic expression and function of Foxc2 and Cx37. Foxc2(+/-)Cx37(-/-) mice have lymphedema in utero, exhibit craniofacial abnormalities, show severe dilation of intestinal lymphatics, display abnormal lacteal development, lack lymphatic valves, and typically die perinatally (outcomes not seen in Foxc2(+/-) or Cx37(-/-) mice separately). We provide a rigorous, quantitative documentation of lymphatic vascular network changes that highlight the specific structural alterations that occur in Foxc2(+/-)Cx37(-/-) mice. These data provide further evidence suggesting that Foxc2 and Cx37 are elements in a common molecular pathway directing lymphangiogenesis.

Aberrant lymphatic endothelial progenitors in lymphatic malformation development

Lymphatic malformations (LMs) are vascular anomalies thought to arise from dysregulated lymphangiogenesis. These lesions impose a significant burden of disease on affected individuals. LM pathobiology is poorly understood, hindering the development of effective treatments. In the present studies, immunostaining of LM tissues revealed that endothelial cells lining aberrant lymphatic vessels and cells in the surrounding stroma expressed the stem cell marker, CD133, and the lymphatic endothelial protein, podoplanin. Isolated patient-derived CD133+ LM cells expressed stem cell genes (NANOG, Oct4), circulating endothelial cell precursor proteins (CD90, CD146, c-Kit, VEGFR-2), and lymphatic endothelial proteins (podoplanin, VEGFR-3). Consistent with a progenitor cell identity, CD133+ LM cells were multipotent and could be differentiated into fat, bone, smooth muscle, and lymphatic endothelial cells in vitro. CD133+ cells were compared to CD133− cells isolated from LM fluids. CD133− LM cells had lower expression of stem cell genes, but expressed circulating endothelial precursor proteins and high levels of lymphatic endothelial proteins, VE-cadherin, CD31, podoplanin, VEGFR-3 and Prox1. CD133− LM cells were not multipotent, consistent with a differentiated lymphatic endothelial cell phenotype. In a mouse xenograft model, CD133+ LM cells differentiated into lymphatic endothelial cells that formed irregularly dilated lymphatic channels, phenocopying human LMs. In vivo, CD133+ LM cells acquired expression of differentiated lymphatic endothelial cell proteins, podoplanin, LYVE1, Prox1, and VEGFR-3, comparable to expression found in LM patient tissues. Taken together, these data identify a novel LM progenitor cell population that differentiates to form the abnormal lymphatic structures characteristic of these lesions, recapitulating the human LM phenotype. This LM progenitor cell population may contribute to the clinically refractory behavior of LMs.

Vascular malformations and hemangiolymphangiomas of the gastrointestinal tract: morphological features and clinical impact

PURPOSE

The purpose of our study was to describe the morphological features of gastrointestinal vascular malformations (VM) and of hemangiolymphangiomas (HLA) and to establish correlations with clinical characteristics. Significant findings: Fifteen VMs and 12 HLAs that were encountered over a period of 22 years, were retrospectively analyzed. The VMs often involved the colon, small intestine, but also the stomach, whereas none of the HLAs arose in the stomach. VMs were more frequently associated with gastrointestinal bleeding, ulcer and were larger than HLAs (p<0.01 for all comparisons). Intralesional hemorrhage and thrombosis were associated with VM (p=0.02 and p=0.05). Surgical resection was performed for 1 HLA and 14 VMs. Vessel abnormalities such as shunt vessels, wall tufts (excrescences) and arterialized veins were more frequent in VMs (p=0.01, p=0.04 and <0.01, respectively) whereas aneurysm-like cavities were observed in both lesion types. Mucosal abnormal vessels were observed only in VMs, whereas HLAs were associated with mucosal lymphatic clusters (p<0.01). Most HLAs contained a D2-40 hetero-geneously positive lymphatic component, were Glut-1 negative and CD31 reactive. There was no statistical difference in occurrence of associated autoimmune, tumoral and cardiovascular conditions between the two patient groups.

CONCLUSIONS

The results of our study suggest that morphological features such as increased size, ulcer, thrombosis, hemorrhage and presence of aberrant mucosal vessels favor the diagnosis of VM. Co-existence of other clinical conditions such as cardiovascular disease, encountered in association with both lesion types, might exacerbate a tendency towards hemorrhage.

Connexin37 and Connexin43 deficiencies in mice disrupt lymphatic valve development and result in lymphatic disorders including lymphedema and chylothorax

Intraluminal valves are required for the proper function of lymphatic collecting vessels and large lymphatic trunks like the thoracic duct. Despite recent progress in the study of lymphvasculogenesis and lymphangiogenesis, the molecular mechanisms controlling the morphogenesis of lymphatic valves remain poorly understood. Here, we report that gap junction proteins, or connexins (Cxs), are required for lymphatic valvulogenesis. Cx37 and Cx43 are expressed early in mouse lymphatic development in the jugular lymph sacs, and later in development these Cxs become enriched and differentially expressed by lymphatic endothelial cells on the upstream and downstream sides of the valves. Specific deficiencies of Cx37 and Cx43 alone or in combination result in defective valve formation in lymphatic collecting vessels, lymphedema, and chylothorax. We also show that Cx37 regulates jugular lymph sac size and that both Cx37 and Cx43 are required for normal thoracic duct development, including valve formation. Another Cx family member, Cx47, whose human analog is mutated in some families with lymphedema, is also highly enriched in a subset of endothelial cells in lymphatic valves. Mechanistically, we present data from Foxc2-/- embryos suggesting that Cx37 may be a target of regulation by Foxc2, a transcription factor that is mutated in human lymphedema-distichiasis syndrome. These results show that at least three Cxs are expressed in the developing lymphatic vasculature and, when defective, are associated with clinically manifest lymphatic disorders in mice and man.

Vascular malformations

Vascular malformations are rare but important skin disorders in children, which often require multidisciplinary care. The goal of this article is to orient pediatricians to the various types of vascular malformations. We discuss the clinical characteristics, diagnostic criteria, and management of capillary, venous, arteriovenous, and lymphatic malformations. Associated findings and syndromes are also discussed briefly.

Polypoid vascular and lymphatic malformation of the duodenum: a case report

Polypoid vascular and lymphatic malformation of the small intestine is rare. We report the case of a polypoid vascular and lymphatic malformation of the duodenum in a 58-year-old woman presenting with post-prandial epigastric discomfort. She did not have common symptoms of intestinal vascular and lymphatic malformation, such as gastrointestinal bleeding, steatorrhea, and hypoalbuminemia. A 5.0x0.8-cm semipedunculated polypoid lesion was found in the duodenal bulb with protrusion into the prepyloric antrum and was successfully removed using an endoscopic snare.

An unusual case of adult airway obstruction from a lymphovenous malformation

Lymphatic, venous, and mixed lymphovenous malformations are low-flow lesions that are present at birth and grow proportionately with the patient. We describe an unusual presentation of a lymphovenous malformation in an adult. A 19-year-old man presented to the emergency department with complaints of recent upper respiratory tract symptoms, increasing left-sided sore throat, voice change, odynophagia, dysphagia, and occasional subjective fevers and blood-tinged sputum. Examination revealed the presence of a left peritonsillar bulge consistent with a peritonsillar abscess; however, findings on needle aspiration were negative. The patient was admitted for intravenous steroid and antibiotic therapy. Within 24 hours, his airway became compromised, and he underwent an awake tracheotomy and biopsy, which showed a lymphovenous malformation. Magnetic resonance imaging the following day revealed a large, poorly circumscribed, heterogeneous left parapharyngeal mass consistent with a vascular malformation. With continuation of the steroids and antibiotics, the lesion regressed, and the patient was subsequently decannulated. At the 1-year follow-up, he exhibited no clinical symptoms, and he was in good health off steroids.

Verrucous lymphovascular malformation versus verrucous hemangioma: controversial nomenclature

The International Society for the Study of Vascular Anomalies (ISSVA) divides congenital vascular anomalies into malformations and tumors and subclassified hemangiomas under tumors. However, evidence shows this accepted classification has not been widely employed. Particularly troublesome is the use of the term hemangioma, commonly used to describe a variety of vascular lesions (both malformations and tumors). The term verrucous hemangioma has been used to describe a congenital vascular anomaly with a progressive verrucous epidermal surface persisting throughout life unless surgically excised. Recent evidence suggests that some of these lesions may share histologic features of both hemangiomas and malformations, thereby causing nosologic confusion. We report a 15-year-old adolescent girl with such a lesion and review the literature and controversy of verrucous hemangiomas. In our case, the most appropriate diagnosis is verrucous lymphovascular malformation. Further testing of similar lesions will be necessary to fully understand the nature and classification of these lesions.

Anatomy of the lymphatics

The lymphatic system is perhaps the most complicated system of Homo sapiens. An introduction to the anatomy, embryology, and anomalies of the lymphatics is presented. The overall anatomy and drainage of the lymphatic vessels in outlined. The topographic anatomy, relations, and variations of the principle vessels of the lymphatic system (the right lymphatic duct, the thoracic duct, and the cisterna chyli) are presented in detail.

Temporal Relationship Between Increased Nuchal Translucency and Enlarged Jugular Lymphatic Sac

OBJECTIVE

To study the relationship between the volume of the jugular lymphatic sacs and nuchal translucency thickness in fetuses with increased nuchal translucency with advancing gestation.

METHODS

Seventy-four fetuses with a nuchal translucency greater than the 95th percentile were examined weekly between 11 and 17 weeks of gestational age. The fetal neck region was studied by ultrasonography, followed by measurement of nuchal translucency and jugular lymphatic sacs. The measurements were analyzed using multilevel analysis. In case of termination of pregnancy postmortem examination was performed.

RESULTS

In 40 euploid fetuses and 34 aneuploid fetuses, 159 measurements of jugular lymphatic sac volume and nuchal translucency thickness were analyzed. The volume of the jugular lymphatic sacs and gestational age showed a quadratic relation, which differed between euploid and aneuploid fetuses (P < .01). The maximum volumes were larger and present longer in fetuses with aneuploidy than in euploid fetuses (P < .01). In case of a cardiac anomaly, jugular lymphatic sac volume was larger than in cardiac normal fetuses (nonsignificant). Furthermore, the development of jugular lymphatic sac volume and increased nuchal translucency were related, whereby an increase of the nuchal translucency preceded enlargement of the jugular lymphatic sacs (P < .001). In each fetus an increase in jugular lymphatic sac volume was followed by a decrease with advancing gestation. The gestational age at maximum jugular lymphatic sac volume differed between fetuses, indicating a fetus-specific pattern. Nuchal translucency development showed a similar pattern. Postmortem examination confirmed distension of the jugular lymphatic sacs in all cases.

CONCLUSION

Increased nuchal translucency is associated with abnormal lymphatic development, in which nuchal translucency enlargement precedes enlargement of jugular lymphatic sacs on ultrasound examination. Aneuploid fetuses have a more disturbed lymph angiogenesis.

LEVEL OF EVIDENCE

III.

[Venous malformations: clinical characteristics and differential diagnosis]

Venous malformations (VM) are localized defects of blood vessels that are due to vascular dysmorphogenesis. These slow-flow lesions can affect any tissue or organ. Clinically, a cutaneous VM is characterized by a bluish mass that is compressible on palpation. Phleboliths are commonly present. Symptoms depend on location and size. VM are often sporadic and isolated, however, they can be associated with other malformations and be part of a syndrome; Klippel-Trenaunay (capillary-lymphatico-venous malformation with limb hypertrophy) is the most common. Glomuvenous malformation (GVM) is another type of venous anomaly. In contrast to VM, GVM is often painful on palpation and not compressible. Clinical diagnosis of VM is often made in the presence of a bluish cutaneous lesion: however, other lesions can mimick VM. The most frequent anomalies are a blue naevus, a hemorrhagic lymphatic malformation, a sub-cutaneous hemangioma or even the presence of dilated superficial normal veins due to underlying venous stenoses. This chapter will detail the clinical characteristics of venous anomalies and their differential diagnosis.

[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.

Tumeurs et malformations vasculaires, classification anatomopathologique et imagerie

The understanding of vascular anomalies (vascular tumours and vascular malformations) was obscured, for a long time, by confusion and uncertainties in nosology and terminology. The International Society for the Study of Vascular Anomalies (ISSVA) recently adopted a classification scheme, clearly separating vascular tumours (hemangiomas of different types) which result from active cell proliferation, from vascular malformations, which are inborn defects in vascular morphogenesis. These two types of lesions have different clinical behaviour and require different diagnostic and therapeutic strategies. The most frequent vascular tumour is infantile hemangioma. Its clinical aspects and evolution are well-known. New data have been recently obtained concerning the phenotype of tumour cells and its histogenesis. Of the numerous new vascular tumours, which have been recently described, only the congenital hemangiomas, the vascular tumours associated with the Maffucci syndrome and the tumours that may be complicated by a profound thrombocytopenia (Kasabach and Merritt phenomenon) will be considered. Vascular malformations can be classified according to the vessel(s) types they are composed of. A classification table is presented, separating the malformations of vascular trunks from tissular malformations which are more intimately embedded in the surrounding tissues. The different syndromes associated with vascular anomalies take also place in this table. The clinical, imaging and histological aspects of the most frequent malformations (capillary, venous, lymphatic and arteriovenous) are presented. This classification intend to clarify the nosology and terminology of the complex field of vascular tumours and malformation and to offer a common language to the different physicians and specialists contributing, preferably with a interdisciplinary approach, to the diagnosis and treatment of these difficult lesions.

Les malformations lymphatiques : aspects cliniques et évolution

Lymphatic malformations (LM) are the most frequent vascular malformations. There are three types of lesions involving lymphatic development that must be included in LM: vascular anomalies and knots (truncal malformations [TLM]); cystic anomalies, superficial or deep, uni- or multicystic (extratruncal malformations [ETLM]) and hemolymphatic anomalies which combine venous, arterial, or capillary malformations with LM. ETLM can be ubiquitously distributed but most are located in the cervical or axillary regions. Most ETLM are diagnosed at birth and in 80-90% of the cases before the age of 2. The clinical aspects are extremely variable: superficial ETLM (vesicular) and deep ETLM, localised or diffuse, mono- or multicystic. TLM are generally located on a lower limb with neonatal lymphatic oedema (often in a polymalformation context). All forms of the hemolymphatic combination can be identified. They are generally located on the limbs and are often unilateral. They are usually sporadic but can also be can be found in polymalformation syndromes (Klippel-Trénaunay, Parkes-Weber, Protée, Maffucci). ETLM generally tend to increase in volume and spread with age with stabilisation at puberty. They do not tend to spontaneously regress. Specific local complications can have serious consequences. They are linked to haemorrhaging, infections and compression phenomena. There can also be complications such as skeletal and soft tissue hypertrophy.

Management of Hemangiomas and Pediatric Vascular Malformations

Pediatric vascular anomalies can be difficult to diagnose and complex to treat. One must be able to distinguish hemangiomas from various vascular malformations, as well as appreciate their dynamic course with time. Thorough understandings of the clinical and diagnostic techniques used to evaluate these lesions are paramount for the treating surgeon. In addition, knowledge of current treatments from watchful waiting to radical extirpation is mandatory. This must all be done in the setting of a developing child. We present a current review of the literature regarding the comprehensive care of pediatric vascular lesions.

An Approach to the Management of Common Vascular Malformations of the Trunk

Vascular anomalies can be classified into two unique groups, hemangiomas and vascular malformations, based on their endothelial properties. The present review will focus on the four most common vascular malformations of the trunk presenting to the Plastic Surgeon: capillary malformations, lymphatic malformations, venous malformations, and arterovenous malformations. We define the trunk as chest, abdomen and back; the principles of breast reconstruction will not be discussed as they have been extensively covered in other publications. Diagnostic and therapeutic modalities will be discussed with pertinent case examples.

Nonimmune idiopathic hydrops fetalis and congenital lymphatic dysplasia

Six newborns that presented at birth with nonimmune hydrops fetalis and for whom no cause could be found were investigated for the presence of lymphatic dysplasia. Careful analysis led to findings of some degree of lymphatic dysplasia in all patients. This suggests that lymphatic dysplasia may represent at least part of the causes that are responsible for the "idiopathic" form of nonimmune hydrops fetalis. Carefully searching for lymphatic dysplasia in these patients, and if indicated in their relatives, as well as establishing the exact nature of the lymphatic dysplasia must be carried out so as to provide proper genetic counseling to families with nonimmune hydrops.

Lymphocytopenia in Children With Lymphatic Malformation

OBJECTIVE

To determine whether an immunologic abnormality exists in patients with lymphatic malformation (LM).

DESIGN

Retrospective case series.

SETTING

Tertiary care pediatric hospital.

PATIENTS

Twenty-one consecutive patients (11 male and 10 female) undergoing LM treatment.

INTERVENTIONS

Clinical data (ie, age, clinical LM stage, radiographic appearance, and histologic findings) were correlated with complete blood cell count and detailed lymphocyte differential. Complete blood cell counts and lymphocyte subsets were measured in 21 and 18 patients, respectively.

RESULTS

The average age at the time of testing was 67 months (range, 1-231 months). The patients were categorized according to LM stage, including 4 (19%) with stage 1, 4 (19%) with stage 2, 4 (19%) with stage 3, 7 (33%) with stage 4, and 2 (10%) with stage 5 disease. Radiographic LM appearance was macrocystic in 6 patients (29%), mixed macrocystic and microcystic in 8 (38%), and microcystic in 7 (33%). Complete blood cell count data demonstrated lymphocytopenia in 6 patients (29%). The results of the lymphocyte subset tests showed concomitant T-, B-, and natural killer (NK)-cell deficiency in 6 (33%) of 18 patients. All 6 patients with T-cell lymphocytopenia had normal neutrophil and platelet counts. Spearman rank and chi(2) analyses showed that LM stage 4 or 5 and microcystic LM were significantly associated with lymphocytopenia (P = .002 and P = .008, respectively). Histologic analysis did not demonstrate increased lymphocytes in any LM specimens.

CONCLUSION

We found T, B, and NK lymphocytopenia in patients with large bilateral or microcystic LM. Although the relationship between lymphocytopenia and infection was not addressed in this study, the recognition of lymphocytopenia in patients with LM may have important clinical and prognostic implications.

Vascular update: Morphogenesis, tumors, malformations, and molecular dimensions

This vascular review is organized under the following headings: vasculogenesis and angiogenesis; vascular endothelial growth factors, their receptors, TIE receptors, and angiopoietins; other factors in blood vessel formation; parallel patterning in blood vessels and nerves; physiological and pathological neovascularization; the role of VEGF receptors in metastasis; anti-angiogenic therapy for tumors; association of blood vessels with fat; vascular malformations and vascular tumors; infantile hemangiomas; congenital hemangiomas; lymphatic malformations; molecular characteristics of some disorders with vascular malformations; Kasabach-Merritt phenomenon; Sturge-Weber syndrome, Klippel-Trenaunay syndrome, and Parkes Weber syndrome; diagnostic and laboratory studies; and future perspectives.

Lymphatic vascular defects promoted by Prox1 haploinsufficiency cause adult-onset obesity

Multiple organs cooperate to regulate appetite, metabolism, and glucose and fatty acid homeostasis. Here, we identified and characterized lymphatic vasculature dysfunction as a cause of adult-onset obesity. We found that functional inactivation of a single allele of the homeobox gene Prox1 led to adult-onset obesity due to abnormal lymph leakage from mispatterned and ruptured lymphatic vessels. Prox1 heterozygous mice are a new model for adult-onset obesity and lymphatic vascular disease.

Lymphatic malformations

Lymphatic malformations are rare forms of vascular anomalies. They are most frequently diagnosed at birth and most often occur in the head and neck area. Their treatment continues to be challenging, and treatment methods continue to evolve. In this article, the embryology of the lymphatic system is reviewed, and the classification of lymphatic malformations and their natural history and treatment are discussed.

Identification of lymphatic endothelium in pediatric vascular tumors and malformations

The distinction between lymphatic and other vascular vessels on microscopic sections is a challenging task. D2-40, a novel antibody, has been reported to be selective for lymphatic endothelium. We studied the specificity and sensitivity of D2-40 in pediatric vascular tumors and malformations. Fourteen lymphatic and 11 vascular lesions were randomly selected and stained with D2-40 and CD31 antibodies. The lymphatic lesions included 6 lymphatic malformations, 5 cystic hygromas (macrocystic lymphatic malformation), 2 lymphovenous malformations, and 1 lymphangioma, and the vascular lesions comprised 3 infantile hemangiomas, 3 Kaposiform hemangioendotheliomas, 2 tufted angiomas, 1 pyogenic granuloma, 1 arteriovenous, and 1 venulocapillary malformations. The staining patterns of the vascular channels were compared. In all lesions D2-40 labeled only the endothelium of thin-walled vascular channels morphologically consistent with lymphatic vessels (25 of 25). No staining of the vascular lesions (0 of 11) or of arteries and veins (0 of 25) was observed. All lymphatic lesions had D2-40-positive vessels; however, the percentage of vessels that stained varied. Five lymphatic lesions showed more than 75% D2-40-positive channels, 5 lesions had approximately 50%, and 4 cases showed fewer than 25% D2-40-positive channels. There was a tendency of more consistent D2-40 staining of small versus large lymphatic channels. CD31 constantly labeled arteries, veins, capillaries, and lymphatics in all lesions and all endothelial cells in the vascular lesions. D2-40 is a very specific antibody for lymphatic endothelium, with variable sensitivity. CD31 more reliably identifies lymphatic endothelium. Currently, D2-40 appears to be a good marker to identify lymphatic vessels in pediatric vascular tumors and malformations.

Surgical management of perineal masses in patients with anorectal malformations

BACKGROUND

The aim of this study was to review the outcome of surgical management of various types of perineal masses encountered in patients with anorectal malformations (ARM).

METHODS

Retrospective review from 2 large pediatric anorectal referral centers.

RESULTS

Twenty-two patients with a perineal mass were identified in more than 2000 patients treated for an ARM over a 15-year period. The 22 patients (4 men) represented all levels of severity of ARMs. The lesions were of 3 types: lipomas (n = 10), vascular anomalies (n = 4), and hamartomas/choristomas (n = 8). The lipomas were carefully removed from between the muscle fibers during the posterior sagittal anorectoplasty. The vascular anomalies (3 of 4 were hemangiomas) underwent magnetic resonance imaging preoperatively, but none were found to invade deeply and all were excised at the time of the posterior sagittal anorectoplasty. The hamartomas/choristomas all occurred in women, and 50% arose as a pedunculated mass from the vulva. The lesions contained tissues such as glia, osteoid, nephrogenic rests, and endocervical-type mucosa. One was initially misinterpreted as a teratoma, prompting a wider excision. This and all subsequent patients have been correctly diagnosed pathologically as having either hamartomas or choristomas, which were not widely excised. Follow-up ranges from 5 months to 12 years. Six of the 10 lipoma patients are continent. One vascular anomaly was re-excised and there was minor wound separation in another. None of the hamartoma/choristoma lesions recurred.

CONCLUSION

The presence of unusual perineal masses can add to the complexity of ARMs; however, most of these lesions can be carefully excised with preservation of the muscle complex and ultimate continence. Hamartomatous lesions can be mistaken for teratomas but do not require aggressive excision with clear margins.

Cerebrofacial venous metameric syndrome (CVMS)�3: Sturge-Weber syndrome with bilateral lymphatic/venous malformations of the mandible

We present a case of Sturge-Weber syndrome with a bilateral lymphatic/venous malformation of the mandible. Modern biology suggests an explanation for such a case. The classification of cerebrofacial venous metameric syndromes (CVMS) enables us to recognise this lesion as involving the most caudal of the cranial metamere (CVMS 3).