[16] In brief, after pretreatment using a microwave with citrate buffer (pH 6), 95°C, for 20 min, blocking endogenous peroxidase, sections were incubated with the primary antibody at Angiogenesis inhibitor 4°C overnight. The Envision+ solution for mouse and rabbit (Dako) was then applied for 30 min at room temperature. The reaction products were visualized using 3-3′-diaminobenizidine tetrahydrochloride (Sigma Chemical, St Louis,

MO, USA) and H2O2. The sections were then lightly counterstained with hematoxylin. Similar dilution of the control mouse or rabbit Immunoglobulin G (Dako) was applied instead of the primary

antibody as a negative control. Positive and negative controls were routinely included. A cut section of the resected tumor showed a nodular lesion of 10 mm in diameter with an ill-defined border (Fig. 2). Color after fixation was light brown, similar to the background liver, and the central part showed congestion. On histology, the nodular lesion had an ill-defined border and hemangiomatous lesions were scattered inside (Fig. 2). Hemangiomatous lesions adjacent to portal tracts were also seen. Sinusoidal dilatation with congestion was observed in the central area of the nodular lesion (Fig. 2). Hepatocytes in the lesion showed a thickened cell layer and increased Lapatinib in vivo cellular density when compared with the background liver, but there was no cellular atypia (Fig. 2). Reticulin fibers were not decreased around hepatic trabeculae. Endothelial cells in the hemangiomatous lesions and dilated sinusoids showed distinct immunoreactivity for CD34. In addition, sinusoidal endothelial cells in the area without sinusoidal

dilatation showed immunoreactivity for CD34, indicating capillarization of sinusoids. The background liver was almost normal and there were few hemangioma-like vessels outside the nodule. There Telomerase were no abnormally thickened arteries or a central stellate scar, so this nodular lesion appeared to be different from the usual FNH. Although the dilated sinusoidal structure resembled inflammatory-type hepatocellular adenoma, immunostaining for SAA was negative. Immunostaining for LFABP and GS did not suggest any other subtypes of hepatocellular adenoma. Taken together, this lesion was diagnosed as a hyperplastic hepatocellular lesion associated with localized hemangiomatosis, including multiple hemangioma-like vessels.