Pediatric hepatic vascular tumors: clinicopathologic characteristics of 33 cases and proposed updates to current classification schemes

Update on the Pathology of Pediatric Liver Tumors: A Pictorial Review

“…These channels are lined by a flattened, minimally, or moderately plump endothelium with small, bland, hyperchromatic nuclei without severe atypia; mitosis is infrequent. Redundancy features such as pseudopapillae formation, mimicking Masson papillary endothelial hyperplasia, are also reported, and some cases may show bilayering [8]. Lesional anastomozing channels are separated by variable amounts of fibrotic stroma.…”

“…HCH occurs most commonly as a solitary lesion in the right hepatic lobe and upon ultrasound showing a large mass with an extensive central infarction, cystic change, hemorrhage, calcifications, and sometimes an arterial feeding vessel that has direct shunts to hepatic veins. The use of magnetic resonance imaging (MRI) and computed tomography (CT) may show lesions with centripetal enhancements [4,7,8]. A diagnosis can be made upon prenatal imaging.…”

“…Histologically, HCH is composed of vague aggregates or lobules of variously sized capillary vessels lined by a single layer of round to oval benign endothelial cells with inconspicuous nucleoli and few pericytes (Figure 2) [8]. These aggregates are often located at the tumor's periphery, and the individual capillaries are separated by fibrotic stroma.…”

“…Three subtypes of HIH are reported, namely focal, multifocal, and diffuse [13]. Although HIH generally follows a benign clinical course, some tumors have been reported to undergo malignant transformation [8].…”

“…Cystic spaces and a fleshy appearance are also known to occur [34,35]. The classic morphological features of angiosarcoma include markedly atypical endothelial cells with high nuclear-to-cytoplasmic ratios, hyperchromatic nuclei, inconspicuous to prominent nucleoli with solid spindled or epithelioid areas, and destructive invasion into the surrounding liver parenchyma and increased mitotic activity (more than the proliferative phase of HIH) (Figure 6) [8]. Hepatic angiosarcoma in children may arise within a non-involuting HIH, and in this context often shows GLUT-1 immunopositivity.…”