Expression of Prox1, Lymphatic Endothelial Nuclear Transcription Factor, in Kaposiform Hemangioendothelioma and Tufted Angioma

Vascular tumors of intermediate malignancy: An update

The term "hemangioendothelioma" is used for endothelial neoplasms of intermediate malignancy and describes a group of rare neoplasms having biologic behavior falling in between that of the benign hemangiomas and fully malignant angiosarcomas. The hemangioendotheliomas fall into several specific, clinicopathologically and genetically distinct entities, specifically epithelioid hemangioendothelioma, kaposiform hemangioendothelioma, papillary intralymphatic angioendothelioma and retiform hemangioendothelioma (hobnailed hemangioendothelioma), pseudomyogenic hemangioendothelioma, composite hemangioendothelioma, and YAP1::TFE3-fused hemangioendothelioma. The clinical, morphologic, immunohistochemical, and genetic features, and the differential diagnosis of each of these rare entities are discussed in this review.

Recent advances in nanomaterial-driven strategies for diagnosis and therapy of vascular anomalies

Nanotechnology has demonstrated immense potential in various fields, especially in biomedical field. Among these domains, the development of nanotechnology for diagnosing and treating vascular anomalies has garnered significant attention. Vascular anomalies refer to structural and functional anomalies within the vascular system, which can result in conditions such as vascular malformations and tumors. These anomalies can significantly impact the quality of life of patients and pose significant health concerns. Nanoscale contrast agents have been developed for targeted imaging of blood vessels, enabling more precise identification and characterization of vascular anomalies. These contrast agents can be designed to bind specifically to abnormal blood vessels, providing healthcare professionals with a clearer view of the affected areas. More importantly, nanotechnology also offers promising solutions for targeted therapeutic interventions. Nanoparticles can be engineered to deliver drugs directly to the site of vascular anomalies, maximizing therapeutic effects while minimizing side effects on healthy tissues. Meanwhile, by incorporating functional components into nanoparticles, such as photosensitizers, nanotechnology enables innovative treatment modalities such as photothermal therapy and photodynamic therapy. This review focuses on the applications and potential of nanotechnology in the imaging and therapy of vascular anomalies, as well as discusses the present challenges and future directions.

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.

Cerebral Tufted Angioma with Gradually Developing Peritumoral Edema: A Case Report

Tufted angioma is a benign vascular tumor in which immature endothelial and pericyte cells and lymphatic vascular endothelium grow. It manifests as a flat, painful erythema that gradually expands mainly on the trunk and extremities. Although tufted angiomas can also occur in other areas of the body and may be more locally invasive, they rarely occur intracranially. A 63-year-old man underwent magnetic resonance imaging (MRI) for a brain check-up 8 years before his visit to our institute, which detected a mass lesion with surrounding cerebral edema in the left frontal lobe. The patient was followed up with annual MRI analysis, which indicated slow tumor growth and gradual development of peritumoral edema. The tumor was treated by gross-total resection. Histological analysis showed a slightly dilated microvascular core surrounded by many capillary aggregates in the brain parenchyma. Immunohistochemical findings indicated that the vascular endothelial cells were positive for CD34 and Brahma-related gene-1 and were surrounded by smooth muscle actin-positive pericytes. These findings were consistent with tufted angioma. Intracranial tufted angioma is uncommon, but it should be considered in the differential diagnosis for intracranial tumorous lesions. Long-term follow-up is necessary to unravel the natural history of the disease.

Malignant Superficial Mesenchymal Tumors in Children

Malignant superficial mesenchymal tumors are a very diverse group of neoplasms with few clinical and radiological discriminatory factors. Hence, some of these cancers are rarely suspected based on clinical and radiological grounds, others may be easily misdiagnosed, and the histological analysis of a biopsy or resection is central in the diagnostic process. In children, the age at presentation is a major element of the differential diagnosis. Some tumors have a very distinct epidemiology, while others may be seen at any age. More recently, the advances in molecular biology have greatly improved the diagnosis of mesenchymal tumors and new entities are still being described. In the present review, we provide an overview of the diversity of malignant superficial mesenchymal tumors in children, including new and/or rare entities. We discuss the important diagnostic features, be they clinical, histological, or molecular. Special attention was given to the genetic features of these tumors, particularly when they were helpful for the diagnosis or treatment.

Case report: Kaposi hemangioendothelioma of the right upper limb with the Kasabach-Merritt phenomenon: A potentially lethal diagnostic challenge

Kaposi hemangioendothelioma (KHE) is a rare vascular neoplasm that presents usually within the first year of life. Because of its rarity and complexity, there is often a delay in diagnosis. KHE could be associated with a life-threatening consumptive coagulopathy named the Kasabach-Merritt phenomenon (KMP). Here, we present the case of a 2-month-old girl who presented with progressive redness and swelling of her right upper limb over 6 weeks. Multiple health practitioners misdiagnosed her condition as an insect bite, cellulitis, and necrotizing fasciitis and gave treatment accordingly, which proved futile. A full blood count revealed bicytopenia of anemia and thrombocytopenia, a normal coagulation cascade, low fibrinogen, and raised D-Dimer levels. The imaging was suggestive of a high-flow vascular tumor likely to be a KHE. Subsequently, she was started on single-agent oral sirolimus with a dose increment to achieve satisfactory therapeutic levels and was treated for 1 year. She successfully completed the treatment regimen and had only transient hypertriglyceridemia, which resolved upon the completion of treatment. Currently, she is in remission 3 years after treatment. Keeping her case as an example, we would like to highlight the potentially lethal misdiagnosis of KHE with KMP, the importance of an early diagnosis of this condition, and the successful treatment outcome with single-agent sirolimus.

Whole Exome Sequencing Identifies Somatic Variants in an Oral Composite Hemangioendothelioma Characterized by YAP1-MAML2 Fusion

Composite hemangioendothelioma (CHE) is considered a borderline malignant vascular tumor defined by an admixture of distinct vascular neoplastic components. A 21-year-old female is presented herein with a 1 cm painless mandibular vestibular mass of less than a year duration. The infiltrating tumor was characterized by dilated vascular channels lined by endothelial cells with bland ovoid or round nuclei exhibiting, occasionally, hobnail/matchstick-like arrangement. Intravascular cell proliferations with hyaline globular deposits were also present. Additionally, lobular spindle and epithelioid cell aggregates, as well as slit-like spaces exhibiting a retiform or angiosarcomatous morphology were observed. Intracytoplasmic signet-ring or lipoblast-like vacuolization was also noted. Mitotic activity was exceptionally rare. Vascular spaces and the stroma featured lymphocytes and plasma cells. Neoplastic cells were positive for CD31, CD34, D2-40 and ERG, negative for CAMTA1 and synaptophysin, while type IV collagen highlighted the plasmalemma of most vessels and hyaline globules. Fluorescence in situ hybridization revealed gene rearrangements in both YAP1 and MAML2 genes, in keeping with a YAP1-MAML2 fusion. Whole exome sequencing (WES) identified three missense mutations FLT1 [p.R1016G], PIK3CA [p.H1047L], and C11orf42 [p.A304P] and a mitochondrial frameshift insertion MT-ND4 [c.1107_1108insC; p.P370fs]. These WES results suggest that FLT1 and/or PIK3CA variants may contribute to tumor growth/transformation while the MT-ND4 variant may relate to proliferation, angiogenesis and/or inhibition of apoptosis.

Case Report: Cutaneous Pleomorphic Lymphangiosarcoma in a Dog Exhibiting Features of Human Composite Hemangioendothelioma

Background: Angiosarcomas are a broad category of vascular origin neoplasms that are poorly characterized in veterinary species. Lymphangiosarcoma (LAS) is an uncommon type of angiosarcoma reported in humans and canines arising from lymphatic endothelium. LAS can be differentiated from other angiosarcomas in dogs based on expression of Prospero-related homeobox gene-1 (PROX-1) or lymphatic vessel endothelial receptor-1 (LYVE-1). Composite hemangioendothelioma (CHE) is a rare angiosarcoma subtype described in people and characterized by a variable biologic behavior and infrequent metastasis. This variant of angiosarcoma histologically combines features of retiform hemangioendothelioma and epithelioid hemangioendothelioma. Information regarding the cytologic and histopathologic appearance and clinical course of dogs with vascular tumors that exhibit features of CHE are unknown. Here, we report a case of pleomorphic LAS with features of CHE arising in a dog and treated with surgery and adjuvant chemotherapy.

Case presentation: A 10-year-old intact male Labrador retriever presented with an approximately 6-cm-diameter cutaneous mass caudal to the left elbow that was progressively growing over 1.5 years. On physical examination, palpable extensions were identified coursing proximally over the triceps with concurrent loco-regional peripheral lymphadenopathy. Fine needle aspirates (FNA) and cytologic assessment of the cutaneous mass, left prescapular, and accessory axillary lymph nodes reported that this appeared to be a metastatic epithelial neoplasm, although a mixed carcinoma or collision tumor could not be excluded. An incisional biopsy of the mass was submitted for histopathology and was consistent with a well-differentiated angiosarcoma with features of CHE. The neoplasm expressed vimentin, CD31, von Willebrand factor (vWf), and PROX-1, supporting the diagnosis of LAS. Complete staging was performed, and no additional metastatic lesions were identified. Left forelimb amputation and lymph node removal were performed. Based on the diagnosis of metastatic LAS, doxorubicin chemotherapy was administered. 7 months post-amputation, the tumor recurred at the amputation site without evidence of metastatic disease.

Conclusion: This report describes a malignant, locally aggressive lymphatic origin vascular tumor in a dog, with features consistent with descriptions of CHE in humans. Cytologic features in this case were discordant with its true mesenchymal etiology, obfuscating diagnosis. The morphologic features of the mesenchymal neoplastic population and immunohistochemistry (IHC) labeling ultimately supported a diagnosis of pleomorphic LAS with features of CHE.

Overexpression Prox1 in HemECs resembles Kaposiform hemangioendothelioma and cytotoxicity of sirolimus in vitro

BACKGROUND

Kaposiform hemangioendothelioma (KHE) is a rare vascular tumor that occurs in children. Prox1 is a specific lymphatic marker for KHE. We intended to establish a Prox1 transgenic cell line resembling KHE and investigate the mechanism of sirolimus in treating KHE.

METHODS

Prox1 was stably expressed in infantile hemangioma cell HemECs. RT-qPCR and Western blot were conducted to measure the expression of target genes. CCK-8, EdU assay, and cell cycle analysis were conducted to detect cell proliferation. Wound healing and transwell assay were used to evaluate cell migration and invasion.

RESULTS

Both mRNA and protein levels of Prox1, LYVE-1, Podoplanin were upregulated in Prox1⁺ HemECs. An acceleration of cell growth and a rise in migration and invasion were observed with Prox1 overexpression. Sirolimus inhibited cell proliferation, promoted apoptosis and led to G1 phase arrest in Prox1⁺ HemECs. The expression of p-mTOR, p-4EBP1, and p-P70S6K decreased and the ratio of LC-3 II/LC-3 I elevated after treatment of sirolimus.

CONCLUSIONS

Stable overexpression of Prox1 in HemECs induced a lymphatic endothelial reprogramming, and enhanced aggressive biological effects, partly resembled the invasion of KHE, and could serve as a novel model for KHE. Sirolimus may block mTOR-mediated pathways and induced autophagy in KHE.

Intracranial kaposiform hemangioendothelioma presenting as epistaxis: a rare case report with review of literature

INTRODUCTION

Kaposiform hemangioendothelioma (KHE) is a rare vascular tumor of intermediate malignancy with tendency for local invasion and recurrence. The tumor almost exclusively occurs in children, especially in infants. Intracranial KHE are extremely rare with only two cases reported in the literature.

REPORT

We report the clinical and pathological features of this rare tumor arising from basitemporal region in a 21-month child. Our case did not present with Kasabach-Merritt phenomenon. Histopathological examination confirmed the diagnosis of KHE.

CONCLUSION

KHE should be considered in the differential diagnosis of intracranial extra-axial neoplasm in children, and histopathological examination plays an important role in distinguishing KHE from its morphologic mimics. It is essential to diagnose KHE due to its locally aggressive nature.

Management of Refractory Mandibular Kaposiform Hemangioendothelioma with Sirolimus: A Case Report and Review of the Literature

Kaposiform hemangioendothelioma (KHE) is a rare vascular neoplasm of intermediate malignancy that generally occurs in infancy and early childhood. Typically, the lesion arises from superficial or deep soft tissues of the extremities, trunk and retroperitoneum. The paucity of reported cases of head and neck KHEs is evidence of the rarity of the disease in this region. We report on the presentation and treatment of KHE in an 11-month-old boy who presented with a mandibular lesion. We include a brief discussion about the differential diagnosis of KHE. Management involved preoperative interventional radiology, surgical excision and chemotherapeutic treatment with Sirolimus. The lesion resolved without evidence of relapse 12 months later.

Vascular Anomalies of the Head and Neck: A Pediatric Overview

Vascular anomalies, further classified into vascular tumors and malformations, often involve the head and neck region of children. These entities may raise diagnostic dilemmas, as they often demonstrate heterogenous and overlapping histologic features. The aim of this paper is to provide an overview of the common vascular anomalies in the head and neck region of children. Specific entities discussed include infantile hemangioma, congenital hemangioma, tufted angioma, kaposiform hemangioendothelioma, and various vascular malformations. Clinicopathologic features and associated molecular associations are reviewed.

Neonatal Vascular Tumors

Vascular tumors are a part of the vascular anomalies spectrum. Vascular malformations are congenital vascular lesions, originating from a mesenchymal stem cell defect and distinguished from vascular tumors by their low cell turnover and lack of invasiveness. They tend to grow in proportion to the child. Vascular tumors are proliferative and range from benign proliferation to malignant tumors. The appropriate differential diagnosis is imperative. Infantile hemangioma can be diagnosed clinically and rarely requires therapy; more rare tumors are difficult to diagnose and treat. This review provides an overview of vascular tumors seen in the neonatal period and summarizes treatment options.

The 2020 WHO Classification of Tumors of Soft Tissue: Selected Changes and New Entities

Soft tissue tumors are a relatively rare and diagnostically challenging group of neoplasms that can have varying lines of differentiation. Accurate diagnosis is important for appropriate treatment and prognostication. In the 8 years since the publication of the 4th Edition of World Health Organization (WHO) classification of soft tissue tumors, significant advances have been made in our understanding of soft tissue tumor molecular biology and diagnostic criteria. The 5th Edition of the 2020 WHO classification of tumors of soft tissue and bone incorporated these changes. Classification of tumors, in general, but particularly in soft tissue tumors, is increasingly based on the molecular characteristics of tumor types. Understanding tumor molecular genetics improves diagnostic accuracy for tumors that have been difficult to classify on the basis of morphology alone, or that have overlapping morphologic features. In many large hospitals in the United States and Europe, molecular tests on soft tissue tumors are a routine part of diagnosis. Therefore, surgical pathologists should be familiar with newly emerging molecular genetic techniques in clinical settings. In the near future, molecular tests, particularly in soft tissue tumor diagnosis, will become as routine during diagnosis as immunohistochemistry is currently. This new edition provides an updated classification scheme and essential diagnostic criteria for soft tissue tumors. Newly recognized entities and subtypes of existing tumor types, several reclassified tumors, and newly defined molecular and genetic data have been incorporated. Herein, we summarize the updates in the WHO 5th Edition, focusing on major changes in each category of soft tissue tumor, and the newly described tumor entities and subtypes.

[Classification of vascular tumours and vascular malformations. Contribution of the ISSVA 2014/2018 classification]

The study of vascular anomalies, "angiomas", vascular tumours and vascular malformations is made difficult by the great variety and confusion of the names used in the literature for these diseases, some of which are rare. The great merit of the classification proposed by the International Society for the Study of Vascular Anomalies (ISSVA), adopted in 2014 and modified in 2018, is to propose a unambiguous nomenclature and to try to group these lesions in a logical way, contrasting with the lists of the usual "classifications". This classification is based on the distinction between proliferative lesions (tumours and reactive lesions) and those which are due to a congenital anomaly of vascular morphogenesis (vascular malformations). It incorporates recent data on the molecular causes of these diseases. The major groups of lesions recognised in this classification will be presented and some lesions of interest briefly discussed. This classification aims to be usable by all medical specialties and applicable to all tissues and organs, even if efforts are still needed to integrate organ-specific names in order to unify the nomenclature and eliminate confusion. Even if it does not solve all the problems in this complex field, the unification of the nomenclature is a major contribution of this classification and pathologists are strongly encouraged to refer to it in daily practice.

Vascular tumors

Vascular tumors are a rare subset of vascular anomalies. These are classified based on their malignant potential or local destruction potential. Classification has been historically difficult and treatment recommendations are based on case series. The purpose of this chapter is to review the presentation, pathologic and imaging characteristics. Treatment recommendations are summarized based on the current literature. Congenital and infantile hemangiomas are covered separately in a separate chapter in this issue.

Kaposiform hemangioendothelioma: current knowledge and future perspectives

Kaposiform hemangioendothelioma (KHE) is a rare vascular neoplasm with high morbidity and mortality. The initiating mechanism during the pathogenesis of KHE has yet to be discovered. The main pathological features of KHE are abnormal angiogenesis and lymphangiogenesis. KHEs are clinically heterogeneous and may develop into a life-threatening thrombocytopenia and consumptive coagulopathy, known as the Kasabach-Merritt phenomenon (KMP). The heterogeneity and the highly frequent occurrence of disease-related comorbidities make the management of KHE challenging. Currently, there are no medications approved by the FDA for the treatment of KHE. Multiple treatment regimens have been used with varying success, and new clinical trials are in progress. In severe patients, multiple agents with variable adjuvant therapies are given in sequence or in combination. Recent studies have demonstrated a satisfactory efficacy of sirolimus, an inhibitor of mammalian target of rapamycin, in the treatment of KHE. Novel targeted treatments based on a better understanding of the pathogenesis of KHE are needed to maximize patient outcomes and quality of life. This review summarizes the epidemiology, etiology, pathophysiology, clinical features, diagnosis and treatments of KHE. Recent new concepts and future perspectives for KHE will also be discussed.

Local suture ligation-assisted percutaneous sclerotherapy for Kasabach-Merritt phenomenon-associated kaposiform haemangioendothelioma

Kaposiform haemangioendotheliomas (KHEs) complicated by the Kasabach-Merritt phenomenon (KMP) are rare and severe neoplastic lesions often associated with locally aggressive disease, consumption coagulopathy and high mortality rates. Current regimens have yet to achieve a satisfactory therapeutic effect. Thus, an effective and minimally invasive approach for treating complex KHE/KMP cases is necessary for clinical management. The present case series describes patients with KHE/KMP who underwent local suture ligation-assisted percutaneous sclerotherapy to minimise surgical trauma and ensure effective treatment. Between September 2015 and September 2017, 3 consecutive patients with KHE/KMP underwent staged local suture ligation-assisted percutaneous sclerotherapy. Of these patients, 2 presented with medical histories of corticosteroid treatment with unsatisfactory outcomes. The patients underwent a stepwise synthetic serial therapy programme consisting of percutaneous sclerotherapy and adjunctive pharmacotherapy accompanied by a suture ligation procedure. Clinical, radiological, pathological and laboratory data were analysed to evaluate the outcomes of the therapy. All patients were successfully managed with the proposed procedure. Significant relief of clinical symptoms and improvements in haematological indicators were achieved. No recurrence or complications were observed during regular follow-up (4, 19 and 28 months). In conclusion, local suture ligation-assisted percutaneous sclerotherapy was demonstrated to be a safe and effective treatment for KHE/KMP, being minimally invasive, involving simple manipulation and providing a clear treatment benefit in certain cases. Further studies involving larger sample sizes are required to thoroughly evaluate the procedure, which can potentially be used as a novel therapeutic option for KHE/KMP treatment.

Congenital tufted angioma: A multicenter retrospective study of 30 cases

BACKGROUND

Recent reports indicate that tufted angioma is a rare vascular neoplasm that manifests more frequently at birth than previously thought. Few studies specifically address congenital presentation.

OBJECTIVES

We analyzed the clinicopathological characteristics, clinical course, and treatment of congenital tufted angioma (cTA) and evaluated variables that were indicative of problematic lesions.

METHODS

We performed an observational retrospective study of 30 patients with cTA in 9 Spanish hospitals over a 14-year period. Histopathology and immunohistochemistry studies were performed.

RESULTS

Congenital tufted angioma mainly affected the limbs (56.67%), followed by the face and/or neck (23.33%). Almost three-quarters of facial cTA were located over the mandibular area. Immunohistochemically, proliferating cells expressed markers of endothelial cells, with some clusters of cells, especially at the periphery of the aggregates, showing positivity for podoplanin. As no associated complications were observed in 66.67% of cases, no treatment was started.

LIMITATIONS

Data were collected retrospectively.

CONCLUSIONS

Our findings emphasize the clinical features and course of cTA. The possibility of cTA should be considered when a poorly defined congenital infiltrative vascular tumor with(out) overlying hirsutism appears over the mandibular area. Location on the face and/or neck requires a more comprehensive workup, since potentially severe complications often appear early.

Proliferative Cells From Kaposiform Lymphangiomatosis Lesions Resemble Mesenchyme Stem Cell-like Pericytes Defective in Vessel Formation

Kaposiform lymphangiomatosis (KLA) is a vascular anomaly featuring lymphatic expansion. It has no known cause, no effective treatment, and is associated with high morbidity. Proliferative cells from 3 KLA patient lesions were characterized relative to adiopose-derived mesenchyme stem cells (ADSCs) and cells derived from a patient with the related disease kaposiform hemangioendothelioma (KHE). KLA cells variably expressed markers of mesenchyme stem cells (CD73, CD90, CD105, CD146) and lacked endothelial cell markers (CD31, CD34) as determined by flow cytometry. They expressed markers of vascular pericytes (neural/glial antigen 2, alpha-smooth muscle actin, platelet-derived growth factor-beta receptor, and CXCL12) as determined by quantitative reverse transcription polymerase chain reaction. Lesion cells transcribed vascular markers VEGFC and VEGFD, as well as VCAM-1, the latter of which was confirmed by flow cytometry, consistent with angiogenic MSC-like pericytes. Furthermore, conditioned medium from each was shown to promote the proliferation of growth factor-starved lymphatic endothelial cells. Unlike kaposiform hemangioendothelioma-derived MSC-like pericytes and ADSCs, KLA isolates were defective in support of vascular network formation in co-cultures with either vascular or lymphatic endothelial cells. Genetic analysis by whole exome sequencing revealed novel variant alleles in 2 populations of KLA cells (BAD, TSC1) that may bear on aberrant pericyte growth and function.

Topical rapamycin (sirolimus) for the treatment of uncomplicated tufted angiomas in two children and review of the literature

The mTOR inhibitor rapamycin is used systemically for the treatment of vascular lesions. We report the first use of topical rapamycin for the successful treatment of two cases of tufted angioma. The evidence for the use of topical rapamycin in other dermatologic conditions is summarized to aid in clinical decision making on preparations and anticipated side effects.

Classification and Pathology of Congenital and Perinatal Vascular Anomalies of the Head and Neck

Accurate histopathologic description in correlation with clinical and radiological evaluation is required for treatment of vascular anomalies, both neoplastic and malformative. It is important to examine current clinical, histologic, and immunophenotypical features that distinguish the major types of congenital and perinatal vascular anomalies affecting the head and neck. General discussions of pathogenesis and molecular diagnosis must also be taken into account. This article provides an overview of the features that distinguish the major types of congenital and perinatal vascular anomalies affecting the head and neck, and summarizes the diagnostic histopathologic criteria and nomenclature currently applied to these lesions.

Classification of Vascular Anomalies: An Update

Vascular anomalies present both a diagnostic and therapeutic challenge to physicians. Identification of these lesions is difficult due to their immense phenotypic variability, and naming conventions for vascular anomalies have historically been inconsistent. Terms such as "hemangioma" are informative when used correctly, but can cause confusion and miscommunication if applied indiscriminately to all vascular anomalies. Accuracy in classification is essential, as both disease course and therapeutic options differ greatly depending on the particular vascular anomaly present. In order for clinicians to properly diagnose and treat patients with these diseases, a unified nomenclature must be employed. This section provides an update on the current classification of vascular anomalies, with clinical descriptions of the most commonly encountered lesions, and clarifies the ambiguous nomenclature present in the existing literature.

Phytochemical Inhibition of Multidrug Resistance Protein-1 as a Therapeutic Strategy for Hemangioendothelioma

AIMS

Hemangiomas are endothelial cell tumors and the most common soft tissue tumors in infants. They frequently cause deformity and can cause death. Current pharmacologic therapies have high-risk side-effect profiles, which limit the number of children who receive treatment. The objectives of this work were to identify the mechanisms through which standardized berry extracts can inhibit endothelial cell tumor growth and test these findings in vivo.

RESULTS

EOMA cells are a validated model that generates endothelial cell tumors when injected subcutaneously into syngeneic (129P/3) mice. EOMA cells treated with a blend of powdered natural berry extracts (NBE) significantly inhibited activity of multidrug resistance protein-1 (MRP-1) compared to vehicle controls. This resulted in nuclear accumulation of oxidized glutathione (GSSG) and apoptotic EOMA cell death. When NBE-treated EOMA cells were injected into mice, they generated smaller tumors and had a higher incidence of apoptotic cell death compared to vehicle-treated EOMA cells as demonstrated by immunocytochemistry. Kaplan-Meier survival curves for tumor-bearing mice showed that NBE treatment significantly prolonged survival compared to vehicle-treated controls.

INNOVATION

These are the first reported results to show that berry extracts can inhibit MRP-1 function that causes apoptotic tumor cell death by accumulation of GSSG in the nucleus of EOMA cells where NADPH oxidase is hyperactive and causes pathological angiogenesis.

CONCLUSIONS

These findings indicate that berry extract inhibition of MRP-1 merits consideration and further investigation as a therapeutic intervention and may have application for other cancers with elevated MRP-1 activity. Antioxid. Redox Signal. 26, 1009-1019.

Kaposiform haemangioendothelioma: a review with emphasis on histological differential diagnosis

Kaposiform haemangioendothelioma (KHE) is a rare, locally aggressive/borderline vascular tumour primarily seen in neonates and children. KHE is occasionally associated with Kasabach-Merritt phenomenon and tends to have a poor clinical prognosis. While the histological features of tufted angiomas and KHE overlap, some believe tufted angiomas are a milder, benign, more localised counterpart of KHE. The other histological differential diagnoses of KHE include infantile haemangioma, congenital haemangioma, spindle cell haemangioma, verrucous malformation/haemangioma, and Kaposi sarcoma. Microscopically, KHE is characterised by confluent nodules of neoplastic spindled endothelial cells involving multiple planes of tissue which are positive for endothelial, lymphatic, and smooth muscle markers. Resection, once thought to be the definitive treatment for KHE, is often unattainable due to the extent of the lesion; thus, single or combination chemotherapies have been used to treat these patients. Sirolimus has recently been reported to be a successful agent to treat refractory and complicated cases of KHE.

Histopathology of Spindle Cell Vascular Tumors

Vascular tumors with a spindled morphology represent a diagnostic challenge in soft tissue pathology. It may be difficult to distinguish certain benign entities in this category from spindled vascular tumors of intermediate malignancy or even spindled variants of angiosarcoma. This article focuses on vascular tumors characterized by a predominantly spindled morphology, including spindle cell hemangioma, acquired tufted angioma (angioblastoma of Nakagawa), kaposiform hemangioendothelioma, Kaposi sarcoma, and spindle cell variants of angiosarcoma.

Kasabach-Merritt Phenomenon: Classic Presentation and Management Options

Kasabach-Merritt phenomenon (KMP) is a rare consumptive coagulopathy associated with specific vascular tumors, kaposiform hemangioendothelioma, and tufted angioma. Kasabach-Merritt phenomenon, characterized by profound thrombocytopenia, hypofibrinogenemia, elevated fibrin split products, and rapid tumor growth, can be life-threatening. Severe symptomatic anemia may also be present. With prompt diagnosis and management, KMP can resolve and vascular tumors have been shown to regress. This review highlights the clinical presentation, histopathology, management, and treatment of KMP associated with kaposiform hemangioendothelioma, and less frequently tufted angioma. A classic clinical case is described to illustrate the presentation and our management of a patient with KMP.

Bullous Kaposiform Hemangioendothelioma Masquerading as Aplasia Cutis Congenita

We present the case of a male infant with violaceous bullae on the scalp that were initially thought to be bullous aplasia cutis but at 3 months of age were diagnosed as a kaposiform hemangioendothelioma. This diagnosis should be considered when evaluating newborns with bullous plaques on the scalp that do not heal in the first 2-3 weeks of life. Kaposiform hemangioendothelioma (KHE) is a rare vascular tumor that typically presents as a violaceous to purpuric plaque at birth or early infancy. It may be associated with Kasabach-Merritt phenomenon (KMP), a potentially life-threatening consumptive coagulopathy.

A Critical Analysis of Eleven Periocular Lobular Capillary Hemangiomas in Adults

PURPOSE

To provide a critical analysis of a series of periocular lobular capillary hemangiomas in adults, outlining characteristic clinical and histopathologic patterns in comparison with those of other vascular tumors of adults and children.

DESIGN

Retrospective observational case series.

METHODS

Review of clinical data, hematoxylin-eosin-stained sections, and immunohistochemical studies of smooth muscle actin (SMA), D2-40, CD34, and glucose transporter 1 (GLUT-1).

RESULTS

The 7 female and 4 male patients were diagnosed with periocular lobular capillary hemangioma at a median age of 39 years (range, 17-82 years). The tumors were small (3-14 mm, median size 6 mm) and well circumscribed, arose over the course of weeks to months, and developed most commonly in the canthal region, followed by the upper eyelid skin. The tumors were all composed microscopically of repeating units of various sizes (lobules) consisting of CD34-postive, GLUT-1-negative endothelial cells and SMA-positive pericytes arranged in macro- or microlobules. Some foci also exhibited ectatic vessels or diffuse, nonlobular capillary proliferations. Excision was curative without recurrence.

CONCLUSION

Although capillary hemangiomas are more common in children, lobular capillary hemangiomas can also arise in the periocular region of adults. Some histopathologic features of these lesions are shared with those of infantile hemangioma and tufted angioma of children, but features of the clinical presentation and the results of immunohistochemical staining patterns are distinctive.

Abdominal Kaposiform Hemangioendothelioma Associated With Lymphangiomatosis Involving Mesentery and Ileum: A Case Report of MRI, CT, and 18F-FDG PET/CT Findings

Kaposiform hemangioendothelioma (KH) is a rare vascular tumor of intermediate malignancy that occurs mainly in the childhood. Adult patients with KH are rare. Imaging findings of KH have rarely been reported before. We present magnetic resonance imaging (MRI), computed tomography (CT), and fluorine-18-fluorodeoxyglucose (F-FDG) positron emission tomography (PET)/CT findings in an adult patient with KH associated with lymphangiomatosis involving mesentery and ileum.A 22-year-old female complained of a 9-month history of intermittent melena, weakness, and palpitation. Laboratory tests revealed anemia and hypoproteinemia. Fecal occult blood test was positive. Abdominal enhanced MRI and CT showed a large abdominal mass involving mesentery and ileum. On enhanced MRI, there were many hypervascular nodules in the mass. On FDG PET/CT, the mass and the nodules showed slight FDG uptake. Small bowel capsule endoscopy showed numerous grape-shaped red nodules in the luminal wall of the involved ileum. The patient underwent resection of the abdominal mass and a segment of the ileum invaded by the abdominal mass. KH arising within lymphangiomatosis involving mesentery and ileum was confirmed by pathology. After surgery, the patient's symptoms improved.This is the first case of KH associated with lymphangiomatosis involving mesentery and ileum. In this case, the lymphangiomatosis overshadowed the small tumor nodules resulting in unusual imaging findings. Familiarity with these imaging findings is helpful for diagnosis and differential diagnosis of KH.

Integrative meta-analysis identifies microRNA-regulated networks in infantile hemangioma

BACKGROUND

Hemangioma is a common benign tumor in the childhood; however our knowledge about the molecular mechanisms of hemangioma development and progression are still limited. Currently, microRNAs (miRNAs) have been shown as gene expression regulators with an important role in disease pathogenesis. Our goals were to identify miRNA-mRNA expression networks associated with infantile hemangioma.

METHODS

We performed a meta-analysis of previously published gene expression datasets including 98 hemangioma samples. Deregulated genes were further used to identify microRNAs as potential regulators of gene expression in infantile hemangioma. Data were integrated using bioinformatics methods, and genes were mapped in proteins, which were then used to construct protein-protein interaction networks.

RESULTS

Deregulated genes play roles in cell growth and differentiation, cell signaling, angiogenesis and vasculogenesis. Regulatory networks identified included microRNAs miR-9, miR-939 and let-7 family; these microRNAs showed the most number of interactions with deregulated genes in infantile hemangioma, suggesting that they may have an important role in the molecular mechanisms of disease. Additionally, results were used to identify drug-gene interactions and druggable gene categories using Drug-Gene Interaction Database. We show that microRNAs and microRNA-target genes may be useful biomarkers for the development of novel therapeutic strategies for patients with infantile hemangioma.

CONCLUSIONS

microRNA-regulated pathways may play a role in infantile hemangioma development and progression and may be potentially useful for future development of novel therapeutic strategies for patients with infantile hemangioma.

Multifocal Lymphangioendotheliomatosis With Thrombocytopenia: Clinical Features and Response to Sirolimus

Multifocal lymphangioendotheliomatosis with thrombocytopenia (MLT) is a recently described glucose transporter 1-negative multifocal vascular disorder with significant morbidity and mortality. However, data are lacking on the clinical spectrum, long-term prognosis, and treatment of MLT. It is often confused with multifocal infantile hemangioma, but the conditions must be differentiated for appropriate assessment and therapeutic management. Treatments for MLT have been disappointing, and the treatments classically used for infantile hemangioma are often ineffective. We report 3 newborn cases featuring various clinical and biological phenotypes of MLT: 1 patient had severe brain involvement and died early; another had no thrombocytopenia; and the third had nearly no skin involvement. Histologically, all were negative for glucose transporter 1 and positive for the lymphatic marker lymphatic vessel endothelial hyaluronan receptor 1 or D2-40 (∼38-kDa O-linked transmembrane sialoglycoprotein podoplanin). Two cases with severe gastrointestinal bleeding were treated with sirolimus 0.1 mg/k per day, which was efficient after the first month of treatment. MLT clinically presents in various forms, and when complicated by widespread or severe extracutaneous involvement, initial aggressive therapeutic intervention is justified. The pathogenesis of MLT remains unclear, but lymphatic differentiation is widely acknowledged. Because of its antiangiogenic properties, including anti-lymphangiogenesis, sirolimus offers an adequate and targeted therapeutic approach for MLT.

Vascular Anomalies Classification: Recommendations From the International Society for the Study of Vascular Anomalies

Vascular anomalies represent a spectrum of disorders from a simple "birthmark" to life- threatening entities. Incorrect nomenclature and misdiagnoses are commonly experienced by patients with these anomalies. Accurate diagnosis is crucial for appropriate evaluation and management, often requiring multidisciplinary specialists. Classification schemes provide a consistent terminology and serve as a guide for pathologists, clinicians, and researchers. One of the goals of the International Society for the Study of Vascular Anomalies (ISSVA) is to achieve a uniform classification. The last classification (1997) stratified vascular lesions into vascular malformations and proliferative vascular lesions (tumors). However, additional disease entities have since been identified that are complex and less easily classified by generic headings, such as capillary malformation, venous malformation, lymphatic malformation, etc. We hereby present the updated official ISSVA classification of vascular anomalies. The general biological scheme of the classification is retained. The section on tumors has been expanded and lists the main recognized vascular tumors, classified as benign, locally aggressive or borderline, and malignant. A list of well-defined diseases is included under each generic heading in the "Simple Vascular Malformations" section. A short definition is added for eponyms. Two new sections were created: one dealing with the malformations of individually named vessels (previously referred to as "truncular" malformations); the second groups lesions of uncertain or debated nature (tumor versus malformation). The known genetic defects underlying vascular anomalies are included in an appendix. This classification is meant to be a framework, acknowledging that it will require modification as new scientific information becomes available.

Pediatric dermatohistopathology--histopathology of skin diseases in newborns and infants

While neonatal skin physiology has been thoroughly examined using non-invasive techniques in recent years, only few systematic studies and review articles addressing the histopathology of neonatal skin have been published thus far. In most cases, histopathological findings of dermatoses in neonatal skin do not significantly differ from those seen in adult skin. Nevertheless, a comprehensive knowledge of embryonic and fetal skin development as well as the microanatomical structure of neonatal skin can contribute to a better understanding of various dermatoses of infancy. In the first part of this review article, we present the histopathological features of such skin diseases, which, though generally rare, almost exclusively appear during the first weeks of life due to distinctive structural and functional features of neonatal skin. The second part is dedicated to classic dermatoses of infancy and their histopathological features.

Clinical observations in mesh suture treatment for infants of Kasabach-Merritt phenomenon

AIM

This study aims to evaluate the efficacy and adverse effects of the mesh suture treatment for infants of Kasabach-Merritt phenomenon and to report our treatment experience.

METHODS

Of the three patients, two of the cases occurred in the scalp and one occurred in the back of the chest, with platelet counts < 40 × 10⁹ /L before the treatment, reduced fibrinogen levels and increased D-dimer levels. All the three patients underwent the mesh suture treatment of the tumour area. Post-treatment observations were made regarding the surface colour and texture of the tumours, periodic routine blood examination results, fibrinogen and D-dimer levels.

RESULTS

After treatment, the degree of swelling on the tumour surface was reduced, surface tension was decreased, the tumour colour turned pale red from dark red and the skin gradually returned to normal. Two days after treatment, the platelet counts increased to 70 × 10⁹ /L or higher; the platelet count reached a normal level after 1 week in two cases. The fibrinogen level increased in varying degrees after treatment, whereas the D-dimer level was reduced. One case showed a small amount of exudate at the suture area, 1 month after the treatment; improvements were observed 3 days after changing the local dressing. All the patients were followed up for 6 months to 1 year, during which the patients showed complete regression of the lesion and relapse, normal platelet counts and normal fibrinogen and D-dimer levels.

CONCLUSIONS

We recommend the mesh suture treatment as the first treatment of choice for paediatric Kasabach-Merritt phenomenon.

Tufted hemangioma: clinical case and literature review

Tufted hemangiomas are relatively rare benign vascular proliferations that are congenital or appear during the first years of life. Herein we present an additional case of tufted hemangioma that appeared one year after birth and discuss its histopathological criteria and differential diagnosis with malignant vascular proliferations including sarcoma Kaposi, angiosarcoma and kaposiform hemangioendothelioma.

A novel cell migratory zone in the developing hippocampal formation

The hippocampal formation (HF) is a unique structure in the mammalian brain and is subdivided into the dentate gyrus, Ammon's horn, and subiculum by their functions and connectivity in the neuronal circuit. Because behaviors of the neural stem cells, neuronal progenitors, and the differentiating neurons are complex during hippocampal morphogenesis, the differentiation of these subdivisions has not been well understood. In this study, we investigated embryonic and postnatal expression of the proteins Prox1, Math2, and Ctip2, which clearly indicate principal cells of the dentate gyrus (Prox1 positive) and Ammon's horn (Math2 and Ctip2 positive). Expression patterns of Prox1 and Math2 were consistent with previously suggested localization of migratory pathways of the dentate granule cells and hippocampal pyramidal cells. Interestingly, we found intermingling of Prox1-expressing cells and Math2-expressing cells in a cell migratory stream, suggesting previously unknown behaviors of differentiating cells of the HF.

Kaposiform lymphangiomatosis: a distinct aggressive lymphatic anomaly

OBJECTIVE

To describe the clinical and imaging characteristics of a new lymphatic disorder with a unique histological pattern and poor prognosis.

STUDY DESIGN

An observational, retrospective study identified and characterized 20 patients with distinct lymphatic histopathology referred to the Vascular Anomalies Center at Boston Children's Hospital between 1995 and 2011.

RESULTS

The median age at onset was 6.5 years (range, birth to 44 years). Clinical and radiologic findings suggested a generalized process. The most common presentations were respiratory symptoms (50%), hemostatic abnormalities (50%), and an enlarging, palpable mass (35%). All patients had mediastinal involvement; 19 patients developed pericardial (70%) and/or pleural effusions (85%). Extrathoracic disease manifested in bone and spleen and less frequently in abdominal viscera, peritoneum, integument, and extremities. Despite aggressive procedural and medical therapies, the 5-year survival was 51% and the overall survival was 34%. Mean interval between diagnosis and death was 2.75 years (range, 1-6.5 years).

CONCLUSIONS

We describe a clinicopathologically distinct lymphatic anomaly. We propose the term kaposiform lymphangiomatosis (KLA) because of characteristic clusters or sheets of spindled lymphatic endothelial cells accompanying malformed lymphatic channels. The intrathoracic component is most commonly implicated in morbidity and mortality; however, extrathoracic disease is frequent, indicating that KLA is not restricted to pulmonary lymphatics. The mortality rate of KLA is high despite aggressive multimodal therapy.