Discussion

The hepatic sinusoids are vascular spaces lined by endothelial and Kupffer cells that interconnect the distal branches of the hepatic artery with the portal vein since the usual capillaries do not exist in the liver. With hepatic peliosis, a marked dilatation of these sinusoids involve part of or the entire liver.¹ These irregularly shaped blood-filled cavities cause sponge-like transformation of the hepatic parenchyma, which can be visible on the pathological specimens as well as on cross-sectional imaging modalities.^{2 - 6} The dilated sinusoids in peliosis may be 1 to 2 mm to several centimeters in diameter, while larger lesions may have a “pseudotumor” appearance and be complicated by intrahepatic rupture and hemorrhage, and may ultimately require liver transplantation.^{2, 7}

During a contrast-enhanced CT or hepatic angiography, the dilated sinusoids gradually fill with injected contrast material, retain it in the delayed phase of the study, and eventually become isodense throughout the liver ( Figures 1 , 2 ). MRI of hepatic peliosis showed a mottled appearance of the liver, with dilated sinusoids being hypointense on T1, hyperintense on T2, and markedly enhancing after intravenous gadolinium-based contrast agent administration.^{2, 3, 5} The sonographic features of dilated sinusoids are heterogeneously hypoechoic lesions with irregular shapes and well-defined margins.⁴

The exact pathogenesis of peliosis has not been ascertained, and about 50% of cases are considered idiopathic. However, an association with the use of anabolic hormones, oral contraceptives, other medications such as tamoxifen, and chronic debilitating diseases like tuberculosis and cancer has been reported.^{1 - 3}

A similar condition called bacillary peliosis occurs in patients with acquired immune deficiency syndrome who are infected by Bartonella henselae or Bartonella quintana, the gram-negative bacteria causing cat scratch disease. These patients present with concurrent involvement of the liver, spleen, and lymph nodes, and can be treated with antibiotics such as erythromycin.^{2, 8}

Hepatic peliosis is usually asymptomatic and discovered incidentally in patients undergoing imaging studies for unrelated medical reasons.^{2 - 6} Its rare occurrence in infants and children has been reported, but the vast majority of cases involve middle-aged adults and show no gender preference. The observed findings can occasionally diminish or resolve following discontinuation of the responsible medications or causal agents.^{1, 2} However, many patients eventually develop complications owing to liver failure, portal hypertension, intrahepatic hemorrhage, and ascites. Conservative treatment of this patient did not prove beneficial, and the persistent findings on follow-up imaging studies prompted referral for liver transplant as the recommended treatment for diffuse hepatic peliosis.⁹