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One in 10 infants are born with a vascular birthmark each year. Some vascular birthmarks, such as infantile hemangiomas, are common, while vascular malformations, such as capillary, lymphatic, venous, and arteriovenous malformations, are less so. Diagnosing uncommon vascular birthmarks can be challenging, given the phenotypic heterogeneity and overlap among these lesions. Both sporadic and germline variants have been detected in various genes associated with vascular birthmarks. Identification of these genetic variants offers insight into both diagnosis and underlying molecular pathways and can be fundamental in the discovery of novel therapeutic approaches. The PIK3/AKT/mTOR and RAS/MEK/ERK signaling pathways, which mediate cell growth and angiogenesis, are activated secondary to genetic variations in vascular malformations. Somatic variants in TEK (TIE2) and PIK3CA cause venous malformations. Variants in PIK3CA also cause lymphatic malformations as well as a number of overgrowth syndromes associated with vascular anomalies. Variants in GNAQ and GNA11 have been identified in both so-called "congenital" hemangiomas and capillary malformations. RASA1 and EPHB4 variants are associated with capillary malformation-arteriovenous malformation syndrome. This review discusses the genetics of vascular birthmarks, including the various phenotypes, genetic variants, pathogenesis, associated syndromes, and new diagnostic techniques., Competing Interests: Conflict of interest The authors have no potential conflicts of interest to disclose., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Objective: To define the types of hepatic hemangiomas using the updated International Society for the Study of Vascular Anomalies classification and to create a set of guidelines for their diagnostic evaluation and monitoring., Study Design: We used a rigorous, transparent consensus protocol defined by an approved methodology, with input from multiple pediatric experts in vascular anomalies from hematology-oncology, surgery, pathology, radiology, and gastroenterology., Results: In the first section, we define the subtypes of hepatic hemangiomas based on the clinical course, histology, and radiologic characteristics. We recommend against using the term "hemangioma" for any vascular malformations affecting the liver or any hypervascular tumors that are not characterized by the approved definitions. We recommend against using the term "hemangioendothelioma" for infantile or congenital hemangioma. The following 2 sections dedicated to infantile hepatic hemangioma and to congenital hepatic hemangioma individually describe these subtypes in further detail, including complications to be considered during monitoring and respectively recommended screening evaluations., Conclusions: Although institutional variations may exist for specific clinical details, a clear understanding of the diagnosis of hepatic hemangiomas affecting children and the possible complications that require screening during the monitoring period should be standard. As children with hepatic hemangiomas are managed by different medical and surgical specialties, we offer an expert opinion multidisciplinary consensus based on current literature and on data extracted from the liver hemangioma registry., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Cutaneous vascular anomalies are congenital disorders of abnormal vascular development and growth. Infantile hemangioma is a common type of vascular anomalies characterized by the abnormal growth of blood vessels in the early proliferative phase, followed by the gradual spontaneous regression of the lesion in the involuting phase. Over the past decade, significant advances have been made in our understanding of the cellular and molecular mechanisms that control the development, growth, and regression of infantile hemangioma. In this article, we present a comprehensive review of the current knowledge of the pathogenesis of hemangioma as well as promising research horizons and implications for new therapeutic advances., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Infantile hemangiomas are the most common benign tumor of infancy, occurring shortly after birth in 5% to 10% of white infants. Hemangiomas occur in infants of all races but are most common in those who are white. These lesions are preponderant in females compared with males at rates of 3:1 to 5:1. Many hemangiomas are discrete, well-circumscribed masses present in the head and neck. Some hemangiomas are segmental and diffuse, often involving large areas of the extremities or the head and neck. Chorionic villus sampling at 9 to 12 weeks of gestation has been associated with a 21% increased incidence of hemangiomas in infants. Most hemangiomas occur sporadically without a hereditary component. However, in a few families, hemangiomas segregate as a highly penetrant, autosomal dominant trait. Gene linkage studies of familial infantile hemangiomas show evidence of linkage to chromosome 5q31-33.