Peliosis Hepatis

Peliosis hepatis is an uncommon vascular disorder of the liver characterized by multiple blood-filled cysts of various sizes. The cysts may be lined by endothelium (phlebectatic variant)or represent hemorrhagic liver cell necrosis (parenchymal variant).

Peliosis hepatis is associated with hormonal stimulation (steroids, oral contraceptives, tamoxifen, estrogens), immunoglobulin therapy, azathioprine, malignancies, hematologic disorders (Hodgkin disease, multiple myeloma), transplantation, and infections (pulmonary tuberculosis, HIV, Bartonella henselae and Rochalimaea henselae).

The lesions appear homogeneously hypoechoic in patients with a fatty livers and hyperechoic in patients with healthy livers. The lesions will appear heterogeneously hypoechoic when hemorrhagic. Doppler can show hypervascularity within and surrounding the lesions.

The lesions are low-attenuation on noncontrast CT, but can be missed when smaller than 1 cm. Lesions may have increased attenuation in cases of hemorrhage or internal calcification. During the arterial phase there is early globular enhancement with small pools of contrast in the center of the lesions (target sign). During the portal venous phase, the lesions may demonstrate a centrifugal (more common) or centripetal (mimicking hemangioma) progression of enhancement. The phlebectatic variant may have late diffuse homogeneous hyperattenuation, but not the parenchymal variant, since the latter is composed of hemorrhagic parenchymal necrosis. Larger cavities that communicate with sinusoids can have the same attenuation as blood vessels.

MRI findings will depend on the stage of the blood within the lesions. The lesions are usually T1-hypointense and usually T2-hyperintense with foci of high signal from hemorrhagic necrosis. Like CT, the enhancement pattern is typically centrifugal. Delayed phase images may show strong enhancement with a branching pattern representing the vascular component of the lesion.

In contrast to the nonspecific appearance seen on ultrasound, CT, and MR, angiographic findings are unique: Multiple pools of contrast on late arterial phase images that persist on parenchymal and early venous phases.

Differential considerations for multiple hemorrhagic hepatic lesions include:

• Hemorrhagic metastases:
• Hepatic adenomas: Increased risk with glycogen storage diseases, diabetes mellitus, hemochromatosis, acromegaly, oral contraception and anabolic steroids.
• Hepatocellular carcinoma:
• Peliosis hepatis:

References

• Iannaccone R, Federle MP, Brancatelli G, Matsui O, Fishman EK, Narra VR, Grazioli L, McCarthy SM, Piacentini F, Maruzzelli L, Passariello R, Vilgrain V. Peliosis hepatis: spectrum of imaging findings. AJR Am J Roentgenol. 2006 Jul;187(1):W43-52.
• Savastano S, San Bortolo O, Velo E, Rettore C, Altavilla G. Pseudotumoral appearance of peliosis hepatis. AJR Am J Roentgenol. 2005 Aug;185(2):558-9.