Over the past decade, many changes and updates have occurred in the world of vascular anomalies, including their histopathology. An appreciation has developed that a combined team approach is optimal in arriving at a correct diagnosis. Technical advances such as immunohistochemical stains for GLUT1, an excellent marker for infantile hemangioma, and vascular immunostains such as D2-40, PROX1, and vascular endothelial growth factor receptor 3, which distinguish lymphatics from arteries and veins, have been of immense help in daily practice.
"VMs frequently occur in the oral and facial regions and may continue to grow throughout a patient's lifetime5. Furthermore, VMs are characterized by thin-walled and dilated sponge-like channels, luminal thrombi and phleboliths6. VMs may also be associated with several types of syndromes, such as Klippel Trenaunay syndrome and Blue Rubber Bleb Nevus syndrome5. VMs often disrupt the physiological functions of adjacent normal tissues, including the muscles7, bones8 and nerves910. "
[Show abstract][Hide abstract] ABSTRACT: Venous malformations (VMs) are among the most common slow-flow vascular malformations characterized by irregular venous channels, luminal thrombi, and phleboliths. To systematically manifest the disorganized vascular structures in sporadic VMs, we initially evaluated histopathological characteristics, perivascular cell coverage, adhesion molecules expression and vascular ultrastructures. Then, the expression of Tie2 and TGF-β in VMs was detected. Meanwhile, the in vitro studies were performed for mechanism investigation. Our data showed that the perivascular α-SMA(+) cell coverage and expression of adhesion molecules in VMs were significantly decreased compared with those in the normal skin tissues. We also found that the expression and phosphorylation levels of Tie2 were upregulated, whereas TGF-β was downregulated in VMs, and they were negatively correlated. Moreover, the in vitro results also revealed a possible balancing effect between Tie2 and TGF-β, as demonstrated by the findings that Ang-1 (agonist of Tie2) treatment significantly downregulated TGF-β expression, and treatment with recombinant TGF-β could also suppress Tie2 expression and phosphorylation. This study provided strong evidence supporting the disorganized vascular structures and dysregulation of related molecules in sporadic VMs, and demonstrated a possible balancing effect between Tie2 and TGF-β, which might help to develop novel therapeutics for vascular disorganization-related disorders.
[Show abstract][Hide abstract] ABSTRACT: Vascular anomalies in children and adolescents are the most common soft tissue lesions and include reactive, malformative, and neoplastic tumefactions, with a full spectrum of benign, intermediate, and malignant neoplasms. These lesions are diagnostically challenging because of morphologic complexity and recent changes in classification systems, some of which are based on clinical features and others on pathologic findings. In recent decades, there have been significant advances in clinical diagnosis, development of new therapies, and a better understanding of the genetic aspects of vascular biology and syndromes that include unusual vascular proliferations. Most vascular lesions in children and adolescents are benign, although the intermediate locally aggressive and intermediate rarely metastasizing neoplasms are important to distinguish from benign and malignant mimics. Morphologic recognition of a vasoproliferative lesion is straightforward in most instances, and conventional morphology remains the cornerstone for a specific diagnosis. However, pathologic examination is enhanced by adjunctive techniques, especially immunohistochemistry to characterize the type of vessels involved. Multifocality may cause some uncertainty regarding the assignment of "benign" or "malignant." However, increased interest in vascular anomalies, clinical expertise, and imaging technology have contributed greatly to our understanding of these disorders to the extent that in most vascular malformations and in many tumors, a diagnosis is made clinically and biopsy is not required for diagnosis. The importance of close collaboration between the clinical team and the pathologist cannot be overemphasized. For some lesions, a diagnosis is not possible from evaluation of histopathology alone, and in a subset of these, a specific diagnosis may not be possible even after all assembled data have been reviewed. In such instances, a consensus diagnosis in conjunction with clinical colleagues guides therapy. The purpose of this review is to delineate the clinicopathologic features of vascular lesions in children and adolescents with an emphasis on their unique aspects, use of diagnostic adjuncts, and differential diagnosis.
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