Figure 4 Microscopic characteristics of hepatic hemangiomatosis using hematoxylin-eosin and CD34 immunostaining. (A) Low-magnification view showing shreds of normal liver parenchyma infiltrated with fragments of a hemangioma-type vascular tumor containing erythrocyte-filled, various-sized, vascular channels separated by fibrous septa (hematoxylin-eosin; 100×). (B) Higher-magnification view of the boxed area in panel A showing narrow (solid arrows), and extensively dilated (open arrows) pathological vascular spaces filled with erythrocytes and lined by flattened endothelium. The vascular lumina are separated by fibrous stroma forming septa of variable thickness (hematoxylin-eosin; 200×). (C) Dilated vascular spaces are lined by CD34-positive endothelial cells (immunoperoxidase; 200×). (D) Higher magnification of the boxed area in panel C demonstrating the delicate single-layer flat endothelial cells without any signs of cytological atypia (immunoperoxidase; 400×)