Kaposiform hemangioendothelioma and tufted angioma - (epi)genetic analysis including genome-wide methylation profiling

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.

Coexistence of kaposiform hemangioendothelioma and capillary malformation: More than a coincidence? Two case reports

The coexistence of kaposiform hemangioendothelioma (KHE) and capillary malformation (CM) is quite rare, and few relevant studies can be found to confirm whether this phenomenon is accidental. We diagnosed and treated two such patients, revealing interesting phenomena associated with the development of vascular diseases. These cases offer the possibility that the coexistence of KHE and CM is not accidental and open up a new field of research related to pediatric vascular tumors and vascular malformations. Personalization and precision are required in the diagnosis and treatment of such patients, and the present findings provide a reliable theoretical and practical basis for further research on the pathogenesis and therapy of patients with multiple vascular diseases.

Updates in Genetic Testing for Head and Neck Vascular Anomalies

Vascular anomalies include benign or malignant tumors or benign malformations of the arteries, veins, capillaries, or lymphatic vasculature. The genetic etiology of the lesion is essential to define the lesion and can help navigate choice of therapy. . In the United States, about 1.2% of the population has a vascular anomaly, which may be underestimating the true prevalence as genetic testing for these conditions continues to evolve.

Platelet functional abnormalities in pediatric patients with kaposiform hemangioendothelioma/Kasabach-Merritt phenomenon

Kaposiform hemangioendothelioma (KHE) is a rare vascular tumor of infancy that is commonly associated with a life-threatening thrombocytopenic condition, Kasabach-Merritt phenomenon (KMP). Platelet CLEC-2, tumor podoplanin interaction is considered the key mechanism of platelet clearance in these patients. Here, we aimed to assess platelet functionality in such patients. Three groups of 6 to 9 children were enrolled: group A with KHE/KMP without hematologic response (HR) to therapy; group B with KHE/KMP with HR; and group C with healthy children. Platelet functionality was assessed by continuous and end point flow cytometry, low-angle light scattering analysis (LaSca), fluorescent microscopy of blood smears, and ex vivo thrombi formation. Platelet integrin activation in response to a combination of CRP (GPVI agonist) and TRAP-6 (PAR1 agonist), as well as calcium mobilization and integrin activation in response to CRP or rhodocytin (CLEC-2 agonist) alone, were significantly diminished in groups A and B. At the same time, platelet responses to ADP with or without TRAP-6 were unaltered. Thrombi formation from collagen in parallel plate flow chambers was also noticeably decreased in groups A and B. In silico analysis of these results predicted diminished amounts of CLEC-2 on the platelet surface of patients, which was further confirmed by immunofluorescence microscopy and flow cytometry. In addition, we also noted a decrease in GPVI levels on platelets from group A. In KHE/KMP, platelet responses induced by CLEC-2 or GPVI activation are impaired because of the diminished number of receptors on the platelet surface. This impairment correlates with the severity of the disease and resolves as the patient recovers.

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.

How we approach the diagnosis of a vascular anomaly

Vascular anomalies represent a diverse group of complex disorders that can cause significant complications, including coagulopathies, pain, and decreased function. The diagnosis of vascular anomalies is often challenging due to heterogeneity of presenting phenotypes and overlapping clinical features with other pediatric conditions. Pediatric hematologists/oncologists (PHO) are uniquely positioned for an essential role in diagnosing, managing, and coordinating the multidisciplinary care required to maximize the quality of life of these patients. Here, we review the diagnostic approach involved in patients with vascular anomalies and utilize cases to highlight the challenges involved, and how PHOs can play a vital part in the care of these patients.

Kaposiform Lymphangiomatosis: Pathologic Aspects in 43 Patients

Kaposiform lymphangiomatosis is an uncommon generalized lymphatic anomaly with distinctive clinical, radiologic, histopathologic, and molecular findings. Herein, we document the pathology in 43 patients evaluated by the Boston Children's Hospital Vascular Anomalies Center from 1999 to 2020. The most frequent presentations were respiratory difficulty, hemostatic abnormalities, and a soft tissue mass. Imaging commonly revealed involvement of some combination of mediastinal, pulmonary, pleural, and pericardial compartments and most often included spleen and skeleton. Histopathology was characterized by dilated, redundant, and abnormally configured lymphatic channels typically accompanied by dispersed clusters of variably canalized, and often hemosiderotic, spindled lymphatic endothelial cells that were immunopositive for D2-40, PROX1, and CD31. An activating lesional NRAS variant was documented in 9 of 10 patients. The clinical course was typically aggressive, marked by hemorrhage, thrombocytopenia, diminished fibrinogen levels, and a mortality rate of 21%.

Molecular Pathways and Possible Therapies for Head and Neck Vascular Anomalies

Vascular Anomalies are a heterogenous group of vascular lesions that can be divided, according to the International Society for the Study of Vascular Anomalies Classification, into two main groups : Vascular Tumors and Vascular Malformations. Vascular Malformations can be further subdivided into slow-flow and fast-flow malformations. This clinical and radiological classification allows for a better understanding of vascular anomalies and aims to offer a more precise final diagnosis. Correct diagnosis is essential to propose the best treatment, which traditionally consists of surgery, embolization or sclerotherapy. Since a few years, medical treatment has become an important part of multidisciplinary treatment. Genetic and molecular knowledge of vascular anomalies are increasing rapidly and opens the door for a molecular classification of vascular anomalies according to the underlying pathways involved. The main pathways seem to be: PI3K/AKT/mTOR (PIKopathies) and RAS/RAF/MEK/ERK (RASopathies). Knowing the underlying molecular cascades allows us to use targeted medical therapies. The first part of this article aims to review the vascular anomalies seen in the head and neck region and their underlying molecular causes and involved pathways. The second part will propose an overview of the available targeted therapies based on the affected molecular cascade. This article summarizes theragnostic treatments available in vascular anomalies.

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.

Cellular Variant of Kaposiform Lymphangiomatosis: A Report of Three Cases, Expanding the Morphologic and Molecular Genetic Spectrum of this Rare Entity

Kaposiform lymphangiomatosis (KLA) is a very rare form of generalized lymphatic anomaly, consisting of a diffuse proliferation of abnormal, dilated lymphatics and small fascicles of hemosiderin-laden spindled lymphatic endothelial cells. KLA occurs in children and young adults and may present with multicentric disease, pleural and pericardial effusions, and life-threatening coagulopathy. Genetically, KLA most often harbor somatic activating mutations in NRAS. We recently encountered 3 cases of KLA with cellular features, resembling kaposiform hemangioendothelioma (KHE) and studied their clinicopathologic, radiologic and molecular genetic features. The patients (1 male, 2 females; ages 2 years, 2 months, 4 years) presented with multicentric disease involving skin, soft tissue, bone and spleen, and thrombocytopenia/coagulopathy. Advanced imaging studies confirmed multicentric disease. Biopsies (skin, soft tissue, bone, spleen) demonstrated both conventional KLA and much more cellular foci, consisting of sheets, nodules, glomeruloid structures, and "sieve-like" arrays of lymphatic endothelial cells (positive for CD31 and D2-40). Cellular areas superficially resembled KHE but displayed more epithelioid cytology and lacked surrounding hyaline fibrosis and minute platelet aggregates. Molecular genetic studies demonstrated NRAS c.181C>A p.Q61K (Gln61Lys) in 2 specimens from one patient and HRAS p.A59_Q61delinsGGSIL in another. Two patients were treated with sirolimus; all are currently alive with stable disease. We conclude that cellular morphology in KLA, a previously undescribed feature, does not appear to be associated with clinical features, site of disease, mutation type, response to sirolimus, or outcome. Although cellular KLA may mimic KHE, there are sufficient clinical, morphologic, and genetic differences such that these are likely unrelated diseases.

ISSVA Classification of Vascular Anomalies and Molecular Biology

Vascular anomalies include various diseases, which are classified into two types according to the International Society for the Study of Vascular Anomalies (ISSVA) classification: vascular tumors with proliferative changes of endothelial cells, and vascular malformations primarily consisting of structural vascular abnormalities. The most recent ISSVA classifications, published in 2018, detail the causative genes involved in many lesions. Here, we summarize the latest findings on genetic abnormalities, with the presentation of the molecular pathology of vascular anomalies.

The genetics of vascular tumours: an update

Recent molecular advances have shed significant light on the classification of vascular tumours. Except for haemangiomas, vascular lesions remain difficult to diagnose, owing to their rarity and overlapping clinical, radiographic and histological features across malignancies. In particular, challenges still remain in the differential diagnosis of epithelioid vascular tumours, including epithelioid haemangioma and epithelioid haemangioendothelioma at the benign/low-grade end of the spectrum, and epithelioid angiosarcoma at the high-grade end. Historically, the classification of vascular tumours has been heavily dependent on the clinical setting and histological features, as traditional immunohistochemical markers across the group have often been non-discriminatory. The increased application of next-generation sequencing in clinical practice, in particular targeted RNA sequencing (such as Archer, Illumina), has led to numerous novel discoveries, mainly recurrent gene fusions (e.g. those involving FOS, FOSB, YAP1, and WWTR1), which have resulted in refined tumour classification and improved diagnostic reproducibility for vascular tumours. However, other molecular alterations besides fusions have been discovered in vascular tumours, including somatic mutations (e.g. involving GNA family and IDH genes) in a variety of haemangiomas, as well as copy number alterations in high-grade angiosarcomas (e.g. MYC amplifications). Moreover, the translation of these novel molecular abnormalities into diagnostic ancillary markers, either fluorescence in-situ hybridisation probes or surrogate immunohistochemical markers (FOSB, CAMTA1, YAP1, and MYC), has been remarkable. This review will focus on the latest molecular discoveries covering both benign and malignant vascular tumours, and will provide practical diagnostic algorithms, highlighting frequently encountered pitfalls and challenges in the diagnosis of vascular lesions.

Molecular Diagnostics of Vascular Tumors of the Skin

In this article, the authors have reviewed all the recent news regarding how the discovery of some novel and recurrent molecular and genetic changes has modified the classification of some entities and have addressed to the description of new variants of vascular tumors. And even more important, the authors also reviewed on how these findings, in addition to gain insight into the tumoral biology, portend significant clinical consequences not only regarding to their diagnosis but also to their management and prognosis because some of these mutations are potential targets for treatment. The authors have also highlighted immunohistochemical markers can help us as a surrogate marker of those molecular alterations.

Intimal sarcomas and undifferentiated cardiac sarcomas carry mutually exclusive MDM2, MDM4, and CDK6 amplifications and share a common DNA methylation signature

Undifferentiated mesenchymal tumors arising from the inner lining (intima) of large arteries are classified as intimal sarcomas (ISA) with MDM2 amplification as their molecular hallmark. Interestingly, undifferentiated pleomorphic sarcomas (UPS) of the heart have recently been suggested to represent the cardiac analog of ISA due to morphological overlap and high prevalence of MDM2 amplifications in both neoplasms. However, little is known about ISAs and cardiac UPS without MDM2 amplifications and molecular data supporting their common classification is sparse. Here, we report a series of 35 cases comprising 25 ISAs of the pulmonary artery, one ISA of the renal artery and 9 UPS of the left atrium. Tumors were analyzed utilizing the Illumina Infinium MethylationEPIC BeadChip array, enabling copy number profile generation and unsupervised DNA methylation analysis. DNA methylation patterns were investigated using t-distributed stochastic neighbor embedding (t-SNE) analysis. Histologically, all ISAs and UPS of the left atrium resembled extra-cardiac UPS. All cases exhibited highly complex karyotypes with overlapping patterns between ISA and UPS. 29/35 cases showed mutually exclusive amplifications in the cell-cycle associated oncogenes MDM2 (25/35), MDM4 (2/35), and CDK6 (2/35). We further observed recurrent co-amplifications in PDGFRA (21/35), CDK4 (15/35), TERT (11/35), HDAC9 (9/35), and CCND1 (4/35). Sporadic co-amplifications occurred in MYC, MYCN, and MET (each 1/35). The tumor suppressor CDKN2A/B was frequently deleted (10/35). Interestingly, DNA methylation profiling (t-SNE) revealed an overlap of ISA and cardiac UPS. This "ISA" methylation signature was distinct from potential histologic and molecular mimics. In conclusion, our data reveal MDM4 and CDK6 amplifications in ISAs and UPS of the left atrium, lacking MDM2 amplification. We further report novel co-amplifications of various oncogenes, which may have therapeutic implications. Finally, the genetic and epigenetic concordance of ISAs and UPS of the left atrium further supports a shared pathogenesis and common classification.