Hepatic peliosis is a rare benign vascular condition characterised by dilatation of sinusoidal blood filled spaces within the liver. There may be involvement of other organs, most commonly the spleen and bone marrow. It can be seen in a variety of settings and is important as appearances may mimic malignancy.
As the causes of peliosis are varied, the demographics will reflect the underlying cause.
Patients are usually asymptomatic 6 and thus the condition is discovered incidentally on imaging or autopsy. In some instances, lesions may be complicated by haemorrhage presenting acutely, or result in hepatomegaly or liver impairment.
The pathogenesis remains uncertain, with possible aetiologies including the breakdown of the sinusoidal borders, hepatic outflow obstruction and dilatation of the central vein of the hepatic lobule.
Histologically, hepatic peliosis is characterised by multiple mottled blood-filled cyst-like spaces within the liver with associated sinusoidal dilatation 1-2. These vary in size from a <1 mm to several centimetres in diameter.
Macroscopically, the liver appears dark or even purple, and usually, the entire liver is involved to a greater of lesser degree. Focal lesions may demonstrate central areas of haemorrhage.
- idiopathic: 20-50%
- polyvinyl chloride (PVC)
- thorium oxide
- anabolic steroids
- diethylstilbestrol (DES)
- immunoglobulin therapy
- oral contraceptives
- 6-thioguanine (6-TG)
- 6-mercaptopurine (6-MP)
- chronic illness
- infection in AIDS
- bacillary peliosis caused by Bartonella henselae, Bartonella quintana and Rochalimaea henselae
- renal or cardiac transplantation
Unfortunately, appearances are nonspecific with variable enhancement patterns. Typically, there are multiple lesions, ranging from a few large lesions to innumerable small lesions.
Sonographic appearances are nonspecific, usually demonstrating an irregular hypoechoic region/mass 2.
Appearance on pre-contrast CT is variable, depending on liver density, but is usually of multiple hypoattenuating lesions of variable size. Central haemorrhage may lead to areas of hyperattenuation and even dystrophic calcification 1.
Following contrast administration, there is usually globular centripetal or centrifugal arterial enhancement with no washout, the lesion remaining slightly hyperattenuating compared to surrounding liver on portal venous phase 1. Enhancement may be uniform or peripheral or irregular, but in contrast to cavernous hemangioma, it is usually continuous. There is no mass effect on neighbouring hepatic vessels 6.
Signal characteristics may be altered due to the presence of haemorrhage; however, in general:
- T1: typically hypointense (unless complicated by recent haemorrhage)
- T2: hyperintense
- C+ (Gd): enhancement is typical, and is usually centrifugal (from centre outward)
- hypervascular with multiple vascular nodules
Treatment and prognosis
It is important not to drain peliosis, having mistaken it for a hepatic abscess, as haemorrhage can be life threatening 7.
Treatment depends on the cause. When a causative drug/toxin is suspected, withdrawal of that agent may result in resolution. If seen in the setting of HIV/AIDS, antibiotic treatment may be effective in eradicating B. henselae. If focal and haemorrhagic, resection may also be beneficial 1.
History and etymology
From the Greek word pelios, meaning "dusky" or "purple" 1.
General imaging differential considerations include:
- globular discontinuous contrast enhancement tends to be centripetal (periphery first) rather than centrifugal (centre first)
hepatocellular carcinoma (HCC)
- usually bright arterial enhancement with early washout
- fluid component does not enhance
focal nodular hyperplasia (FNH)
- when typical, are easy to distinguish: central scar; homogeneous arterial enhancement (except for scar); delayed enhancement of the scar; isoattenuating on portal venous scanning; strong enhancement at hepatobiliary phase
- may contain fat
- hypervascular metastases
- hepatic sinusoidal dilation: usually the enhancement pattern is different on CT/MR 5
- 1. Iannaccone R, Federle MP, Brancatelli G et-al. Peliosis hepatis: spectrum of imaging findings. AJR Am J Roentgenol. 2006;187 (1): W43-52. doi:10.2214/AJR.05.0167 - Pubmed citation
- 2. Savastano S, San bortolo O, Velo E et-al. Pseudotumoral appearance of peliosis hepatis. AJR Am J Roentgenol. 2005;185 (2): 558-9. AJR Am J Roentgenol (full text) - Pubmed citation
- 3. Elsayes KM, Narra VR, Yin Y et-al. Focal hepatic lesions: diagnostic value of enhancement pattern approach with contrast-enhanced 3D gradient-echo MR imaging. Radiographics. 25 (5): 1299-320. doi:10.1148/rg.255045180 - Pubmed citation
- 4. Maves CK, Caron KH, Bisset GS et-al. Splenic and hepatic peliosis: MR findings. AJR Am J Roentgenol. 1992;158 (1): 75-6. AJR Am J Roentgenol (citation) - Pubmed citation
- 5. Yang DM, Jung DH, Park CH et-al. Imaging findings of hepatic sinusoidal dilatation. AJR Am J Roentgenol. 2004;183 (4): 1075-7. AJR Am J Roentgenol (full text) - Pubmed citation
- 6. Torabi M, Hosseinzadeh K, Federle MP. CT of nonneoplastic hepatic vascular and perfusion disorders. Radiographics. 28 (7): 1967-82. doi:10.1148/rg.287085067 - Pubmed citation
- 7.Cohen GS, Ball DS, Boyd-kranis R et-al. Peliosis hepatis mimicking hepatic abscess: fatal outcome following percutaneous drainage. J Vasc Interv Radiol. 5 (4): 643-5. - Pubmed citation