Ultrastructural lesions of the liver in human peliosis. A report of 12 cases.

Ultrastructural lesions of the liver were studied in 12 patients with peliosis hepatis. This vascular lesion consisted of cavities filled with red blood cells and sometimes lined with an endothelial barrier; the cavities were due to cystic dilatation of the space of Disse and/or sinusoidal lumen. The passage of red blood cells through the endothelial barrier was occasionally demonstrated. Other striking alterations included the presence of numerous blebs on the sinusoidal membrane of the hepatocytes and the existence of multiple cellular layers lining the sinusoids. Perisinusoidal fibrosis appeared on follow-up biopsies in 3 patients. There was no major abnormality of the hepatocytes or of the hepatic venules. These findings suggest that alterations of the sinusoidal barrier might constitute the primary event in peliosis, although secondary changes to increased pressure and hypoxia within the lobules cannot be excluded.