Use of the International Society for the Study of Vascular Anomalies (ISSVA) classification system has been strongly recommended in recent years because of the need for separate therapeutic measures for patients with vascular tumors and malformations. In the ISSVA classification system, vascular tumors, which are neoplastic, are distinguished from vascular malformations, which are caused by vascular structural anomalies and are not neoplastic, on the basis of the presence or absence of neoplastic proliferation of vascular endothelial cells. It is important that radiologists be familiar with the development, diagnosis, and treatment of vascular tumors and malformations, especially the imaging features of low- and high-flow vascular malformations. Some vascular tumors and malformations develop in isolation, whereas others develop within the phenotype of a syndrome. Syndromes that are associated with vascular tumors include PHACE syndrome. Syndromes that are associated with vascular malformations include Sturge-Weber, Klippel-Trénaunay, Proteus, blue rubber bleb nevus, Maffucci, and Gorham-Stout syndromes, all of which demonstrate low flow, and Rendu-Osler-Weber, Cobb, Wyburn-Mason, and Parkes Weber syndromes, all of which demonstrate high flow. Because imaging findings may help identify such syndromes as systemic, it is important that radiologists familiarize themselves with these conditions.

Non-accidental trauma is the leading cause of intracranial hemorrhage (ICH) in infancy. In contrast, ICH as a part of vitamin K deficiency bleeding (VKDB) secondary to hepatobiliary disease is rare, but encountered even in the era of vitamin K (VK) prophylaxis. During 43 months, six cases with ICH were diagnosed as an initial presentation of VKDB. Clinical features and imaging findings of them were retrospectively reviewed. All cases were breastfed and received oral VK prophylaxis. Liver dysfunction was found in five. Brain CT showed hemorrhage in subdural and subarachnoid space in six, parenchyma in three, and ventricle in one. Abdominal ultrasound was positive in four with final diagnoses of biliary atresia in two, neonatal hepatitis in one, and milk allergy in one. Two cases with negative ultrasound were diagnosed as idiopathic VKDB. In conclusion, ICH with secondary VKDB is rare, but important in infancy in the era of VK prophylaxis.

The role of diffusion weighted imaging and apparent diffusion coefficient in intracranial germ cell tumors has not been fully elucidated. The aim of this study was to evaluate whether the ADC correlates with the histologic subtypes of germ cell tumors. We also aimed to investigate whether the ADC values can predict treatment response. The authors retrospectively analyzed the ADC values of the enhancing and solid regions of germ cell tumors. The absolute ADC values and the normalized ADC values were compared among different histologic diagnoses. The ADC values before and after the first course of chemotherapy were also compared between the different prognostic groups. Ten patients were included in the study. The median age at diagnosis was 9.3 years (range 5.3-13.8 years). There were four patients with germinoma and six patients with nongerminomatous germ cell tumor (NGGCT) including five mixed germ cell tumors and one immature teratoma. The mean absolute and normalized ADC values (×10(-3) mm(2)/s) were significantly lower in germinomas [0.835 ± 0.065 (standard deviation) and 1.11 ± 0.096, respectively] than in NGGCTs (1.271 ± 0.145 and 1.703 ± 0.223, respectively) (p = 0.01). The ADC values before and after the first course of chemotherapy were available in four patients. The ADC value after the first chemotherapy had a tendency to increase more in patients who eventually demonstrated complete response with chemotherapy than in patients who required second-look surgery. Assessment of the ADC values of germ cell tumors is considered to facilitate differentiation of histological subtypes of germ cell tumors. Evaluation of the ADC may also be useful for predicting treatment response.

A child with vein of Galen aneurysmal malformation (VGAM) presented with cardiac failure in the neonatal period. The family history revealed his mother to have hereditary hemorrhagic telangiectasia. The child underwent an endoglin genetic analysis after the newborn period, which eventually demonstrated an endoglin mutation. The pathogenesis of VGAM is currently unknown. The findings of this case suggest that an endoglin mutation might be linked with VGAM.

The International Society for the Study of Vascular Anomalies (ISSVA) classification is becoming the international standard classification system for vascular tumors and vascular malformations. The ISSVA classification strictly distinguishes vascular tumors (neoplastic lesions) from vascular malformations (non-neoplastic lesions) based on whether there is a proliferation of vascular endothelial cells present, and it is an extremely useful classification system for determining therapeutic measures. For vascular tumors, it is clinically significant in terms of discriminating infantile hemangioma and rapidly involuting congenital hemangioma, which are expected to spontaneously regress, from other vascular tumors requiring treatment. Needless to say, clinical courses are important for diagnosis, and it is also important for radiologists to understand imaging findings on vascular tumors because such tumors have unique findings on diagnostic images. In this paper, vascular tumors are classified based on the ISSVA classification, and clinical and imaging findings are reviewed.