Infantile hemangioma is a proliferation of β4-negative endothelial cells adjacent to HLA-DR-Positive cells with dendritic cell morphology

Cutaneous vascular tumors: an updated review

Cutaneous vascular tumors constitute a heterogeneous group of entities that share overlapping morphologic and immunohistochemical features, which can be diagnostically challenging for pathologists and dermatopathologists. Our understanding and knowledge of vascular neoplasms have improved over time, resulting in both a refinement of their classification by the International Society for the Study of Vascular Anomalies (ISSVA) and an improvement in the accurate diagnosis and clinical management of vascular neoplasms. This review article aims to summarize the updated clinical, histopathological, and immunohistochemical characteristics of cutaneous vascular tumors, as well as to highlight their associated genetic mutations. Such entities include infantile hemangioma, congenital hemangioma, tufted angioma, spindle cell hemangioma, epithelioid hemangioma, pyogenic granuloma, Kaposiform hemangioendothelioma, retiform hemangioendothelioma, pseudomyogenic hemangioendothelioma, Kaposi sarcoma, angiosarcoma, and epithelioid hemangioendothelioma.

Examination of oral hemangiomas by intraoral ultrasonography

OBJECTIVES

Oral hemangioma is a benign vascular tumor characterized by the presence of numerous blood vessels. We aimed to examine the clinical and ultrasonographic findings of patients diagnosed with oral hemangioma in our ultrasonography (USG) archive, retrospectively.

METHODS

This study was conducted by examining 20 patients diagnosed with oral hemangioma and underwent USG examination in the Department of Oral and Maxillofacial Radiology of Atatürk University Faculty of Dentistry from 2016 to 2020. All patients had intraoral and radiographic examinations. Patients pre-diagnosed clinically oral hemangioma were evaluated as intraoral with USG. The intraoral USG examinations were performed using both the B-mode and the color Doppler mode.

RESULTS

The mean age of the patients was 42.4 ± 19.14 years; 16 patients were female and four were male. The lesions were mostly observed on the alveolar mucosa (30%), followed by the buccal mucosa (25%), the lower lip (15%), the mouth floor (15%), the tongue (15%). In intraoral USG examinations of all oral hemangiomas, we detected submucosal located, well-defined, lobulated, non-capsule, hypo-isoechoic, heterogeneous lesion areas. Additionally, while we detected only peripheral blood flow in 6 (30%) of 20 patients, we detected both internal and peripheral blood flow in 14 (70%).

CONCLUSIONS

In our study, the examination of the oral hemangiomas with the intraoral probe and the color Doppler mode was very helpful in the differential diagnosis. Although histopathology has an important place in definitive diagnosis, particularly intraoral USG can provide sufficient information for the diagnosis of oral hemangiomas.

Neurosurgery in paediatric strokes

Paediatric strokes are a different entity owing to the difference in pathological entity causing the stroke as well as difficulty in treatment and management due to the presence of a growing brain and small vascular volume making surgery and endovascular intervention dangerous. Yet, the high neuronal plasticity coupled with unique surgical and endovascular procedures makes surgery in these conditions rewarding with improving morbidity and mortality statistics. The field is young and dynamic leading to constant change and updating. We attempt to review the current recommendations with our own experience in paediatric neurosurgery for paediatric strokes and present an overview of common conditions causing paediatric strokes. A brief review of the literature is also supplied for reference.

Integrin β4 Is an Effective and Efficient Marker in Synchronously Highlighting Lymphatic and Blood Vascular Invasion, and Perineural Aggression in Malignancy

Lymphovascular invasion (LVI) and perineural invasion (PNI) are 2 important pathologic parameters and need to be accurately assessed in multiple malignancies. Integrin β4, a member of the integrin family, has been reported to be positively expressed in vascular endothelia, peripheral nerves, and a collection of epithelia. However, little is known about the effectiveness of β4 immunostaining on the recognition of LVI and PNI. Herein, we explored the applicability of β4 immunostaining in stomach, thyroid, and breast cancers. Parallel immunostaining of D2-40, CD34, and S-100 was performed as controls for lymphatic endothelia, vascular endothelia, and neural fibers, respectively. The results demonstrated that β4 concurrently stained the lymphatic and vascular endothelia, and the peripheral nerves. Both LVI and PNI were clearly and accurately outlined by β4 immunostaining. β4 was also expressed in the majority of tumor cells, enabling recognition of LVI and PNI encroached by small tumor clusters. In contrast to D2-40 and CD34, β4 staining was not observed in stromal cells, and therefore it facilitated differentiation between the shrinkage cleft and LVI. According to our results, β4 staining strikingly increased the diagnostic accuracy and interobserver concordance for LVI and PNI compared with hematoxylin and eosin staining alone. Finally, the applicability of β4 was confirmed in 9 other types of malignancies, including cancers of the colon, prostate, esophagus, lung, kidney, uterus, tongue, bladder, and liver. Collectively, β4 is a reliable marker for synchronous detection and diagnosis of LVI and PNI.

An update of 77 cases diagnosed as oral hemangiomas based on GLUT-1 positivity

OBJECTIVES

To evaluate cases diagnosed as "oral hemangiomas" based on the immunohistochemical expression of human glucose transporter protein (GLUT-1) and on histopathological features, and to investigate whether the classification proposed by the ISSVA was used correctly to classify these lesions.

MATERIAL AND METHODS

All cases stored in the archives of an Oral Pathology Service and diagnosed as "oral hemangiomas" were reviewed. Seventy-seven cases were analyzed regarding the expression of GLUT-1. GLUT-1(+) specimens were classified as true infantile hemangioma (IH) and GLUT-1(-) specimens were reclassified based on their histopathological features. The nomenclature of these lesions was evaluated and some cases were reclassified.

RESULTS

Only 26 (33.8%) of the specimens were indeed IHs. Among the GLUT-1(-) specimens, 20 (26.0%) were reclassified as pyogenic granulomas (PGs) and 31 (40.2%) as vascular malformations. Considering the previously applied nomenclature, only 47.5% of the cases initially diagnosed as "hemangiomas" were IHs. In the group of "capillary hemangiomas", most cases (56.2%) were PGs. Among the three "cellular hemangiomas", two were PGs and one was IH. Most (88.8%) "cavernous hemangiomas" were vascular malformations.

CONCLUSION

Careful and parameterized review of cases of vascular anomalies is necessary using auxiliary tools such as GLUT-1, since the exclusive use of histopathological findings might be insufficient to differentiate some anomalies.

CLINICAL RELEVANCE

Accurate clinical examination and the use of biomarkers such as GLUT-1 are essential for the diagnosis.

Arrested Development: Infantile Hemangioma and the Stem Cell Teratogenic Hypothesis

BACKGROUND

Early-life programming is defined by the adaptive changes made by the fetus in response to an adverse in utero environment. Infantile hemangioma (IH), a vascular anomaly, is the most common tumor of infancy. Here we take IH as the tumor model to propose the stem cell teratogenic hypothesis of tumorigenesis and the potential involvement of the immune system.

OBJECTIVES

Teratogenic agents include chemicals, heavy metals, pathogens, and ionizing radiation. To investigate the etiology and pathogenesis of IH, we hypothesized that they result from a teratogenic mechanism. Immature, incompletely differentiated, dysregulated progenitor cells (multipotential stem cells) are arrested in development with vasculogenic, angiogenic, and tumorigenic potential due to exposure to teratogenic agents such as extrinsic factors that disrupt intrinsic factors via molecular mimicry. During the critical period of immunological tolerance, environmental exposure to immunotoxic agents may harness the teratogenic potential in the developing embryo or fetus and modify the early-life programming algorithm by altering normal fetal development, causing malformations, and inducing tumorigenesis. Specifically, exposure to environmental agents may interfere with physiological signaling pathways and contribute to the generation of IH, by several mechanisms.

DISCUSSION

An adverse in utero environment no longer serves as a sustainable environment for proper embryogenesis and normal development. Targeted disruption of stem cells by extrinsic factors can alter the genetic program.

CONCLUSIONS

This article offers new perspectives to stimulate discussion, explore novel experimental approaches (such as immunotoxicity/vasculotoxicity assays and novel isogenic models), and to address the questions raised to convert the hypotheses into nontoxic, noninvasive treatments.

Vertebral hemangiomas in the thoracic spine of multiple sclerosis patients are connected with fewer demyelinating lesions at the same level. Possible impact on pathophysiology and clinical course

OBJECTIVES

Mechanisms of angiogenesis regulate multiple sclerosis (MS) lesions' evolution, displaying both neuroprotective and harmful effects. Factors traditionally considered as purely angiogenic, like vascular endothelial growth factor (VEGF), exert complex heterogenous actions on both neural and vascular malformation-derived tissues. Aim of this retrospective study was to examine, for the first time, potential associations between the presence of common vascular malformations, like vertebral hemangiomas (VHs), and several clinico-radiological MS parameters.

METHODS

236 MS patients who were followed in our Outpatient Clinic were recruited in this study. Outcome measures concerned demographics, disease-derived variables, and MS-lesions' distribution in VHs - positive and negative patients. All data were collected retrospectively. Potential correlations were assessed with univariate statistical analyses (p = 0.05), followed by multivariate regression models, for purposes of confounder-effects elimination.

RESULTS

VH presence showed significant negative correlations with presence of MS lesions in the thoracic (p = 0.005 for thoracic VHs), but not the cervical cord. Trends towards negative associations of VH presence with subtentorial MS lesions and positive family history for MS were also observed.

DISCUSSION

Our observations suggest that VH presence may reduce the risk of thoracic demyelinating lesions in MS patients. They could be explained as part of a multifaceted angiogenic process, concomitantly enhancing neural repair and abnormal hemangioma vascularization.

A hydrogel-endothelial cell implant mimics infantile hemangioma: modulation by survivin and the Hippo pathway

Microvascular endothelial cells cultured in three-dimensional hydrogel scaffolds form a network of microvessel structures when implanted subcutaneously in mice, inosculate with host vessels, and over time remodel into large ectatic vascular structures resembling hemangiomas. When compared with infantile hemangiomas, similarities were noted, including a temporal progression from a morphological appearance of a proliferative phase to the appearance of an involuted phase, mimicking the proliferative and involutional phases of infantile hemangioma. Consistent with the progression of a proliferative phase to an involuted phase, both the murine implants and human biopsy tissue exhibit reduced expression of Ajuba, YAP, and Survivin labeling as they progressed over time. Significant numbers of CD45+, CD11b+, Mac3+ mononuclear cells were found at the 2-week time point in our implant model that correlated with the presence of CD45+, CD68+ mononuclear cells observed in biopsies of human proliferative-phase hemangiomas. At the 4-week time point in our implant model, only small numbers of CD45+ cells were detected, which again correlated with our findings of significantly diminished CD45+, CD68+ mononuclear cells in human involutional-phase hemangiomas. The demonstration of mononuclear cell infiltration transiently in the proliferative phase of these lesions suggests that the vascular proliferation and/or regression may be driven in part by an immune response. Gross and microscopic morphological appearances of human proliferative and involutional hemangiomas and our implant model correlate well with each other as do the expression levels of Hippo pathway components (Ajuba and YAP) and Survivin and correlate with proliferation in these entities. Inhibitors of Survivin and Ajuba (which we have demonstrated to inhibit proliferation and increase apoptosis in murine hemangioendothelioma cell tissue culture) may have potential as other beneficial treatments for proliferating infantile hemangiomas. This implant model may have potential as a modest through-put screen for testing and development of therapeutics targeted at the proliferative phase of infantile hemangiomas, reducing the subsequent postinvolutional scarring or deformities sometimes associated with these lesions.

Importance of GLUT1 in differential diagnosis of vascular anomalies

Vascular anomalies (VAs) include a group of distinct lesions, such as vascular system congenital malformations, as well as benign and malignant vascular tumors. These lesions may present similar clinical and histopathological features, leading to mistaken diagnoses and incorrect treatment choices. It is important that professionals responsible for monitoring the development of VAs conduct precise investigations and use the appropriate terminology. The human glucose transporter protein isoform 1 (GLUT1) has been proposed as a tool to aid in differential diagnosis between different VAs, given that it is a sensitive and specific marker for identification of infantile hemangiomas (HIs) in any organ. This article presents a review of the literature on this protein as an effective tool for identification and possible differential diagnosis between several VAs.

Current classification and terminology of pediatric vascular anomalies

OBJECTIVE

The purpose of this article is to review new terminology to diagnose, classify, and refer patients with vascular anomalies for additional imaging, intervention, and treatment.

CONCLUSION

In recent decades, much has been learned regarding the histopathology, cause, and treatment of vascular anomalies. As information has been gleaned, a new classification system has emerged that divides vascular anomalies into neoplasms and malformations. Its utility is based on accurate initial diagnosis that correlates consistently with clinical presentation, disease course, and treatment.

M2-polarised macrophages in infantile haemangiomas: correlation with promoted angiogenesis

AIMS

The pathogenesis of infantile haemangiomas (IHs) is still far from clear despite the fact that they are common vascular tumours distinctive for their perinatal presentation, rapid growth during the first year of life and subsequent slow involution.

AIMS

To determine the role of M2-polarised macrophages in IHs.

METHODS

M2-polarised macrophages were initially identified in 20 specimens of IHs by both immunochemistry and immunofluorescence for CD68 and CD163. The immunopositive M2-polarised macrophages in different phases of IHs were quantified, and further analysed for their correlations with the expression levels of Ki67, vascular endothelial growth factor (VEGF) and macrophage colony-stimulating factor (M-CSF).

RESULTS

The infiltrating macrophages in proliferative IHs were predominantly CD68/CD163, thus of the M2-polarised phenotype, whereas the density of these cells was significantly decreased in the involuting IHs. The high density of M2-polarised macrophages in proliferative IHs was closely correlated with overexpression of M-CSF, one of the cytokines considered to induce macrophages to polarise towards an M2 phenotype. The infiltrating M2-polarised macrophages probably contributed to the proliferation and angiogenesis of haemangioma endothelial cells, as evidenced by their close correlations with the immunoreactivities of Ki67 and VEGF.

CONCLUSIONS

Results indicate that the infiltrating M2-polarised macrophages may contribute to the progression of IHs by promoting the angiogenic process.

Study of the etiopathogenesis and differential diagnosis of oral vascular lesions by immunoexpression of GLUT-1 and HIF-1α

BACKGROUND

To investigate whether the immunohistochemical expression of GLUT-1 and HIF-1α is related to the diagnosis and pathogenesis of oral vascular lesions.

STUDY METHODS

Thirty cases each of pyogenic granuloma (PG) and hemangioma were studied. Antibodies against GLUT-1 and HIF-1α were detected by immunoperoxidase staining in 3-μm histological sections, and the results were analyzed qualitatively and quantitatively, respectively. Positive and negative cells were counted, and the mean number of positive cells was calculated for each case.

RESULTS

The initial diagnosis of hemangioma was maintained in only 7 (23%) of the 30 cases studied, which were positive for GLUT-1. The remaining 23 cases were reclassified as vascular malformation (VM) (n = 13) and PG (n = 10) due to the absence of staining. The endothelium of blood vessels was negative for GLUT-1 in all cases initially diagnosed as PG (n = 30). The percentage of HIF-1α-positive cells was higher in cases of PG, followed by hemangiomas and VMs (P = 0.005).

CONCLUSIONS

Histological features are not sufficient to establish the correct diagnosis of oral hemangiomas, and an accurate anamnesis is essential in these cases. In addition, these findings demonstrate that vascular lesions express mediators of angiogenesis, HIF-1α, and suggest that his process may play a role in the pathogenesis of vascular.

Infantile hemangiomas: an update

Infantile hemangioma (IH) is a common vascular tumor of infancy. Although benign, infants with IH can experience complications including ulceration, visual and airway impairment, and residual scarring and disfigurement. It is often challenging for clinicians to predict which tumors are in need of systemic treatment. However, data from various demographic and other studies have revealed further insights into this tumor. This article reviews the identification, evaluation, and management of high-risk IHs, including the indications for treatment and the use of systemic treatments such as corticosteroids, β-blockers, and vincristine.

Recent progress in studies of infantile hemangioma

A hallmark of infantile hemangioma, the most common tumor of infancy, is its dramatic growth after birth, by diffuse proliferation of immature endothelial cells, followed by spontaneous regression. The growth and involution of infantile hemangioma is quite different from other vascular anomalies, which do not regress and can occur at any time during life. Some hemangioma lesions can be extremely disfiguring and destructive to normal tissue and may even be life-threatening. Unfortunately, existing therapeutic approaches have limited success and significant adverse effects of some treatment modalities limit their use. Better understanding of the pathogenesis of hemangioma will enable the development of better therapeutic strategies. Here, we review recent studies and new hypotheses on the pathogenesis of the tumor. Detailed mechanisms of activated vascular endothelial growth factor signaling in tumor cells, identification of their origin and characterization of multipotent stem cells that can give rise to infantile hemangioma are shedding new light on this intriguing vascular tumor.

Progenitor cells in infantile hemangioma

Infantile hemangioma is a vascular tumor that occurs in 5% to 10% of infants of European descent. A hallmark of infantile hemangioma is its life cycle, which is divided into 3 stages. The proliferating phase spans in the first year of postnatal life and is characterized by cellular masses without a defined vascular architecture and nascent blood vessels with red blood cells evident within the lumenal space. The involuting phase begins at 1 year of age and continues for 3 to 5 years. Proliferation slows or stops in this phase, and histologic examination shows that the blood vessel architecture becomes more obvious and vessel size is enlarged. The involuted phase reaches 5 to 8 years of age, at which point blood vessels are replaced with a fibrofatty residuum and capillary-sized channels. The growth and involution life cycle of infantile hemangioma are very different from other vascular tumors and vascular malformations, which do not regress and can occur at any time during childhood or adult life. Many laboratories have reported on the endothelial characteristics of the cellular masses that are prominent in the proliferating phase of infantile hemangioma, as well as their immature appearance. These studies, along with isolation and characterization of hemangioma-derived cell populations with progenitor cell properties, have lead to an emerging hypothesis that hemangioma is caused by an abnormal or delayed differentiation of mesodermal progenitor cells into the disorganized mass of blood vessels. In this paper, we discuss the literature that supports this emerging hypothesis.

Vasculogenesis in infantile hemangioma

Infantile hemangioma is a vascular tumor that occurs in 5-10% of infants of European descent. A defining feature of infantile hemangioma is the dramatic growth and development into a disorganized mass of blood vessels. Subsequently, a slow spontaneous involution begins around 1 year of age and continues for 4-6 years. The growth and involution of infantile hemangioma is very different from other vascular tumors and vascular malformations, which do not regress and can occur at any time during childhood or adult life. Much has been learned from careful study of the tissue morphology and gene expression patterns during the life-cycle of hemangioma. Tissue explants and tumor-derived cell populations have provided further insight to unravel the cellular and molecular basis of infantile hemangioma. A multipotent progenitor cell capable of de novo blood vessel formation has been isolated from infantile hemangioma, which suggests that this common tumor of infancy, long considered to be a model for pathologic angiogenesis, may also represent pathologic vasculogenesis. Whether viewed as angiogenesis or vasculogenesis, infantile hemangioma represents a vascular perturbation during a critical period of post-natal growth, and as such provides a unique opportunity to decipher mechanisms of human vascular development.

The placenta theory and the origin of infantile hemangioma

The pathogenesis of infantile hemangioma is unknown. In recent years, much of the focus has been placed at identifying the cell type(s) responsible for tumor initiation. New discoveries in infantile hemangioma suggest an involvement of progenitor cells in the pathogenesis of this vascular tumor. Both embryonic and extra-embryonic tissues have been postulated as potential sources for these progenitor cells. This review focuses on the placental theory, which proposes that a fetal placental progenitor is the cell type of origin for infantile hemangioma. Special emphasis will be placed on placental vasculogenesis and the presence and transit of placental progenitor cells during gestation.

Hypoxia, hormones, and endothelial progenitor cells in hemangioma

Hemangiomas are the most common tumor of infancy, and although the natural history of these lesions is well described, their etiology remains unknown. One current theory attributes the development of hemangiomas to placentally-derived cells; however, conclusive evidence to support a placental origin is lacking. While placental tissue and hemangiomas do share molecular similarities, it is possible that these parallels are the result of analogous responses of endothelial cells and vascular progenitors to similar environmental cues. Specifically, both tissue types consist of actively proliferating cells that exist within a low oxygen, high estrogen environment. The hypoxic environment leads to an upregulation of hypoxia inducible factor-1alpha (HIF-1alpha) responsive chemokines such as stromal cell derived factor-1alpha (SDF-1alpha) and vascular endothelial growth factor (VEGF), both of which are known to promote the recruitment and proliferation of endothelial progenitor cells. Increased hormone levels in the postpartum period further potentiate the growth of these lesions. In this model, increased stabilization of HIF-1 in concert with increased levels of estrogen create a milieu that promotes new blood vessel development, ultimately contributing to the pathogenesis of infantile hemangiomas.

Pathogenesis of infantile haemangioma: new molecular and cellular insights

Infantile haemangioma is the most common tumour of infancy, yet the origin of these lesions remains controversial and the predictable life cycle is poorly understood. Much new information on infantile haemangiomas has emerged over the past decade, but experts continue to debate fundamental features, including cell of origin, nonrandom distribution, and mechanisms regulating the sometimes explosive growth and slow involution. The development of useful laboratory models has been difficult, in turn restricting the development of treatment options available to the clinician. Despite this, new research and creative thinking has spawned several hypotheses on the origin of these tumours and their interesting clinical behaviour, including suggestions of an intrinsic defect in local endothelial cells, a contribution of circulating endothelial progenitors or haemangioblasts, embolisation of shed placental cells and developmental field defects. While no single hypothesis seems to describe all features of infantile haemangioma, continued research seeks to integrate these ideas, create a better understanding of these important tumours and bring new treatments to the clinic.

Prevalence of oral hemangioma, vascular malformation and varix in a Brazilian population

Hemangioma, vascular malformation and varix are benign vascular lesions, common in the head and neck regions. Studies about the prevalence of these lesions in the oral cavity are scarce. The aim of this study was to estimate the prevalence of and to obtain clinical data on oral hemangioma, vascular malformation and varix in a Brazilian population. Clinical data on those lesions were retrieved from the clinical forms from the files of the Oral Diagnosis Service, School of Dentistry, Federal University of Minas Gerais, Brazil, from 1992 to 2002. Descriptive analysis was performed. A total of 2,419 clinical forms in the 10-year period were evaluated, of which 154 (6.4%) cases were categorized as oral hemangioma, oral vascular malformation or oral varix. Oral varix was the most frequent lesion (65.6%). Females had more oral hemangioma and oral varix than males. Oral vascular malformation and oral varix were more prevalent in the 7th and 6th decades, respectively. Oral hemangioma and oral varix were more prevalent in the ventral surface of the tongue and oral vascular malformation, in the lips. Oral hemangioma was treated with sclerotherapy (54.5%), and vascular malformation was managed with sclerotherapy and surgery (19.4% each). The data of this study suggests that benign vascular lesions are unusual alterations on the oral mucosa and jaws.

Overexpression of Notch1 ectodomain in myeloid cells induces vascular malformations through a paracrine pathway

We previously reported that truncation of Notch1 (N1) by provirus insertion leads to overexpression of both the intracellular (N1(IC)) and the extracellular (N1(EC)) domains. We produced transgenic (Tg) mice expressing N1(EC) in T cells and in cells of the myeloid lineage under the regulation of the CD4 gene. These CD4C/N1(EC) Tg mice developed vascular disease, predominantly in the liver: superficial distorted vessels, cavernae, lower branching of parenchymal vessels, capillarized sinusoids, and aberrant smooth muscle/endothelial cell topography. The disease developed in lethally irradiated normal mice transplanted with Tg bone marrow or fetal liver cells as well as in Rag-/- Tg mice. In nude mice transplanted with fetal liver cells from (ROSA26 x CD4C/N1(EC)) F1 Tg mice, abnormal vessels were of recipient origin. Transplantation of Tg peritoneal macrophages into normal recipients also induced abnormal vessels. These Tg macrophages showed impaired functions, and their conditioned medium inhibited the proliferation of liver sinusoid endothelial cells in vitro. The Egr-1 gene and some of its targets (Jag1, FIII, FXIII-A, MCP-1, and MCP-5), previously implicated in hemangioma or vascular malformations, were overexpressed in Tg macrophages. These results show that myeloid cells can be reprogrammed by N1(EC) to induce vascular malformations through a paracrine pathway.

GLUT-1 in oral benign vascular lesions

AIM

To investigate the accuracy of histological diagnosis of oral hemangioma, oral vascular malformation and oral pyogenic granuloma according to immunohistochemical evaluation of the human erythrocyte-type glucose transporter protein (GLUT-1), and to observe the immunoexpression of this protein in oral varix.

MATERIALS AND METHODS

Immunohistochemistry for GLUT-1 was performed in 93 histologically diagnosed cases of oral benign vascular lesions: 17 vascular malformations, 19 hemangiomas, nine varix, and 48 pyogenic granulomas. Descriptive analyses were performed.

RESULTS

None of the cases of the oral benign vascular lesions evaluated were immunopositive to GLUT-1. The 19 cases histologically diagnosed as oral hemangioma that showed negative staining to GLUT-1 were reclassified as oral pyogenic granuloma or oral vascular malformations. The histological evaluation itself is not enough to obtain the correct diagnosis of oral HEM as none of the sample cases were true hemangioma. All sample cases with initial vascular malformation or pyogenic granulomas classification were negative to GLUT-1, demonstrating the accuracy of histological diagnosis of these lesions itself. Oral varix showed negative staining to GLUT-1 in blood vessels.

CONCLUSIONS

GLUT-1 is an useful, effective and important auxiliary marker for the diagnosis of oral benign vascular lesions.

CLINICAL RELEVANCE

This study showed that histological diagnosis alone is not sufficient to correct diagnoses of oral hemangioma. Moreover, immunohistochemistry to GLUT-1 is a useful and easy diagnostic method that may be used to avoid such misdiagnosis. Accurate diagnosis of these oral lesions has an important clinical relevance allowing: (1) correct management, (2) adequate communication among the multidisciplinary team (dentist, dermatologist, pediatrist, radiologist, pathologist, and surgeon), (3) understanding of the biological behavior of the lesions, and (4) facilitate the development of new therapeutic modalities. Thus, supporting the use of this marker in medical and dentistry communities is warranted.

Morphologic, phenotypic and functional characteristics of endothelial cells derived from human hepatic cavernous hemangioma

BACKGROUNDS/AIMS

The pathogenesis of cavernous hemangiomas is largely unknown, and it is speculated that abnormal vasculogenesis and angiogenesis may be involved. In this study, the characteristics of cavernous hemangioma endothelial cells (CHECs) derived from the human liver were analyzed in terms of morphology, phenotype and function and compared with human liver sinusoidal endothelial cells (LSECs).

METHODS AND RESULTS

By transmission electron microscopy, abnormally expanded endoplasmic reticulum (ER) and similarly arranged cytoplasmic vacuoles were only found in CHECs. Phenotypic analysis showed that the expression of alphavbeta3 was significantly increased in CHECs. mRNA expression of vascular endothelial growth factor A, and angiopoietins 1 and 2 was significantly increased in CHECs compared to LSECs. The functional analysis indicated that CHECs released more vascular endothelial growth factor A, produced significantly more pro-matrix metalloproteinase 2 (pro-MMP2) and activated MMP2, and exhibited higher procoagulant and fibrinolytic activities compared with LSECs. Confocal microscopy revealed that MMP2 was concentrated in some cytoplasmic granules of CHECs and was consistent with the distribution of expanded ER. CHECs exhibited more activated angiogenesis capacity and formed abnormal capillary-like structures in vitro.

CONCLUSION

These results suggested that endothelial cells (ECs) derived from human cavernous hemangiomas differ from normal ECs in morphology, phenotype and function.

The pathogenesis of hemangiomas: a review

LEARNING OBJECTIVES

After reading this article, the participant should be able to: 1. Differentiate between hemangiomas and vascular malformations. 2. Describe arguments for the trophoblast origin of hemangiomas. 3. Give arguments for the angioblast theory for the origin of hemangiomas. 4. Identify key genes involved in the origin of hemangiomas.

BACKGROUND

Hemangiomas of infancy are common endothelial tumors. They differ from vascular malformations in their tissue architecture and biological properties. To date, there is no universally accepted theory that explains the pathogenesis and pathophysiology of hemangiomas.

METHODS

Theories from the medical literature from 1981 to 2004 were gathered, categorized, and reviewed.

RESULTS

Current research is mostly on the cellular and genetic levels. The most authoritative theories focus on angioblast origins, trophoblast origins, mutations in cytokine regulatory pathways, and field defects as the cause of the deranged angiogenesis of hemangiomas.

CONCLUSIONS

To date, no single theory can easily explain all the characteristics of hemangiomas, such as predilection for the female sex, usual occurrence after birth, spontaneous involution, abnormal tissue architecture, and distribution within a developmental field. Hemangiomas are probably the final common expression of several pathophysiological mechanisms taking effect alone or in combination.

Myeloid cells in infantile hemangioma

Little is known about the pathogenesis of infantile hemangiomas despite the fact that they are relatively common tumors. These benign neoplasms occur in as many as 1 in 10 births, and although rarely life threatening, hemangiomas can pose serious concerns to the cosmetic and psychosocial development of the afflicted child. Ulceration, scarring, and disfigurement are significant problems as are encroachment of the ear and eye, which can threaten hearing and vision. The precise mechanisms controlling the rapid growth observed in the first months of life and the spontaneous involution that follows throughout the course of years remain unknown. In this report we demonstrate the presence of large numbers of hematopoietic cells of the myeloid lineage in proliferating hemangiomas and propose a mechanism for the observed evolution of these lesions that is triggered by hypoxia and involves the participation of myeloid cells. We report the results of experiments using myeloid markers (CD83, CD32, CD14, CD15) that unexpectedly co-labeled hemangioma endothelial cells, providing new evidence that these cells are distinct from normal endothelium.

Infantile hemangioma is a proliferation of LYVE-1-negative blood endothelial cells without lymphatic competence

Infantile hemangiomas are common benign vascular tumors that exhibit a characteristic history of rapid proliferation in the first year of life and slow spontaneous involution during early childhood. The causative pathogenic event responsible for the abnormal endothelial proliferation remains elusive. The recent discovery of an immature phenotype of proliferating hemangioma endothelial cells due to the exclusive expression of the lymphatic endothelial hyaluronan receptor LYVE-1 led to the proposal that infantile hemangiomas are the result of a primary defect in endothelial cell maturation. To test this hypothesis, we looked for the expression of the lymphatic endothelial cell-specific markers LYVE-1, Prox-1, podoplanin and D2-40 in beta4 integrin-negative proliferating and beta4 integrin-positive involuting infantile hemangiomas. As beta4 integrin proved to be a suitable marker for staging infantile hemangiomas, we used it in combination with clinical and histological criteria to objectively determine the proliferative and involutional phases. In immunohistochemical and immunofluorescent stains, hemangioma vessels were negative for all lymphatic endothelial cell-specific markers tested during both proliferation and involution. LYVE-1 immunoreactivity, however, was found in the dense network of perivascular HLA-DR-positive cells with dendritic cell morphology that are supposed to play a role in hemangiogenesis by releasing pro- and antiangiogenic factors. Notably, this LYVE-1 staining failed to correlate with the growth status of infantile hemangiomas. Our results do not support the notion that LYVE-1 expression was restricted to the proliferative phase and downregulated during involution. Thus, LYVE-1 does not seem to be a reliable marker for proliferating infantile hemangiomas. We conclude that the suggested intrinsic defect in endothelial cell maturation is unlikely the cause for the post-natal rapid growth in infantile hemangiomas. In addition, the lack of lymphatic endothelial cell-specific markers implies that infantile hemangiomas are tumors of blood vessels without lymphatic competence.

Evidence by molecular profiling for a placental origin of infantile hemangioma

The origin of the pathogenic endothelial cells in common infantile hemangioma is unknown. We show here that the transcriptomes of human placenta and infantile hemangioma are sufficiently similar to suggest a placental origin for this tumor, expanding on recent immunophenotypical studies that have suggested this possibility [North, P. E., et al. (2001) Arch. Dermatol. 137, 559-570]. The transcriptomes of placenta, hemangioma, and eight normal and diseased tissues were compared by hierarchical and nonhierarchical clustering analysis of >7,800 genes. We found that the level of transcriptome similarity between placenta and hemangioma exceeded that of any other tissue compared and paralleled that observed between a given tissue and its derived tumor, such as normal and cancerous lung. The degree of similarity was even greater when a subset of endothelial cell-specific genes was analyzed. Genes preferentially expressed in both placenta and hemangiomas were identified, including 17-beta hydroxysteroid dehydrogenase type 2 and tissue factor pathway inhibitor 2. These data demonstrate the value of global molecular profiling of tissues as a tool for hypothesis-driven research. Furthermore, it suggests that the unique self-limited growth of infantile hemangioma may, in fact, mirror the lifetime of placental endothelium.

Hemangiomas of infancy: clinical and biological characteristics

Hemangiomas of infancy are common in the general pediatric population, are usually easily diagnosed, and generally do not require treatment. However, a small but significant percentage of hemangiomas of infancy may develop complications, including infection or ulceration. In addition, hemangiomas located in some anatomic regions may be associated with other anomalies and therefore require more careful monitoring and earlier intervention to prevent permanent sequelae. This review focuses on distinguishing hemangiomas from vascular malformations and delineates the natural history of hemangiomas of infancy, with an emphasis on identifying those hemangiomas that require additional evaluation and closer follow-up. Current treatment modalities, including the use of systemic steroids and the pulsed-dye laser, are discussed. In addition, several conditions that often present with cutaneous hemangiomas are described, including PHACES syndrome and neonatal hemangiomatosis. Finally, an assessment is made of the current understanding of the biology of hemangioma proliferation and involution, including the role of endothelial growth factors and GLUT1, a new marker for hemangiomas of infancy.

Basic science and clinical aspects of vascular anomalies

PURPOSE OF REVIEW

Patients with vascular and lymphatic anomalies are often 'medical orphans' ascertained through distinct medical specialists. Multidisciplinary vascular anomalies programs provide focused expertise in diagnosis and treatment for patients. National and international workshops on vascular anomalies are fostering clinical and basic science research to enhance our understanding of vascular development and vascular anomalies. Herewith is presented an update of recent advances in the study of vascular/lymphatic anomalies.

RECENT FINDINGS

New original findings include (1) the identification of distinct cell surface markers and other cellular properties in hemangiomas and vascular malformations relevant to vascular development, (2) the discovery of novel genetic mutations and susceptibility genes in patients with vascular anomalies, (3) recognition of new risk stratifications and clinical issues for patients with hemangiomas and vascular malformations, and (4) the elucidation of sequelae from the disorders as well as side effects of recent and previous therapies for vascular anomalies.

SUMMARY

Vascular anomalies are an attractive model for the study of human disorders of vasculogenesis and angiogenesis. The etiology of these disorders is unclear and likely represents a multifactorial process. Clinical clues are leading to scientific investigations that may enable targeted therapies, prevention strategies, or both.

Update on hemangiomas and vascular malformations

PURPOSE OF REVIEW

Our knowledge base in the area of vascular anomalies is growing rapidly. With greater understanding of classification and diagnosis, as well as with the numerous areas of research bringing further awareness on the complexity of these lesions, we are improving our ability to treat them. We will attempt in this article to summarize the developments in the field of vascular anomalies over the last year.

RECENT FINDINGS

Emphasis on correct classification is still a high priority in the literature and yet there remains a great deal of misinformation. Many new developments in the basic science of these lesions are allowing better understanding of why these lesions occur while improving our management in these patients. Advances in laser surgery as well as sclerotherapy techniques have improved our ability to treat extensive lesions and also improve patients' quality of life.

SUMMARY

Many new and exciting areas of discovery occur almost daily in the field of vascular anomalies. Due to the breadth of this topic, it is certain that not all articles can be reviewed however the author has tried to present the most recent and clinically relevant breakthroughs in the field.