Ultramicrostructure of hepatic cavernous hemangioma and its correlation with clinical characteristics

AIM: To explore the origin for cavernous hemangioma of the liver (CHL) from the angle of ultramicrostructure, and probe the relationship between CHL ultramicrostructure and the clinical characteristics. METHODS: A total of 8 CHL samples were selected, 1 of which 1 was prepared using routine method, while the other 7 samples was firstly stained by scytodepsic acid before routine management. After the ultrathin sections were prepared by LKB-V ultramicrotome, transmission electron microscope H-600 and JEOL-100SX and scanning electron microscope KYKY-2000 were used to observe the changes of tissue ultrastructure. RESULTS: In CHL samples, endothelial cell monolayer covered the inner wall of blood sinus which was circuitous and showed labyrinth-like structure. The normal endothelial cells were thin and flat with pinocytotic vesicle, microfilament and fewer cell organelles. There were tight and bridge corpuscle junction. Elastic fibers were located under the endothelial cells, while collagenoblasts and smooth muscle cells were observed in tunica media. Collagen fibers were rich in tunica media and theca externa. These structures were similar to those of arteriole. The endothelial cells of CHL tissues were swelled with nucleoli moving aside, and pillar-like blood sinus existed. Cystoid changes of rough endoplasmic reticulum lasted till the necrosis of endothelial cells occurred. A great amount of collagen fibers proliferated in interstitial substance, which divided the elastic fibers and filled the blood sinus cavity in the position of necrotic endothelial cells through fibrosis. There was no normal hepatic cells and sinus hepaticus in CHL tissues. There were no hepatic lobules in CHL, and double blood-supply system didn't exist. CONCLUSION: CHL is caused by vascular malformation of liver arteriole, and the blood-supply of CHL is through artery. Circuitous and labyrinth-like structure of the blood sinus cavity can elucidate the characteristics of its imaging results, including hepatic angiography and computed tomography. Anaplasia of endothelial cells and proliferation of collagen fibers in interstitial substance leads to the fibrosis and analosis of CHL, which is the main mechanism of few natural disruptions in CHL.