What is peliosis hepatis?

What is Peliosis Hepatis?

Peliosis hepatis is a rare vascular liver condition characterized by multiple blood-filled cystic cavities distributed randomly throughout the liver parenchyma that are not lined by endothelial cells. 1, 2, 3

Pathological Definition

• The defining histologic feature is the presence of large blood-filled spaces within the liver tissue that lack an endothelial cell lining, distinguishing them from true vascular structures 1
• These cavities result from damage to sinusoidal cells, with marked sinusoidal dilatation often observed concomitantly 1
• The blood-filled spaces are distributed randomly throughout the liver parenchyma rather than following a specific anatomic pattern 3, 4

Clinical Significance and Presentation

The condition is clinically important because it can present with minimal hepatic dysfunction but may lead to life-threatening complications including spontaneous liver rupture, intra-abdominal hemorrhage, and hepatic failure. 2, 5

• Many cases remain asymptomatic and are discovered incidentally on imaging or at autopsy 6
• When symptomatic, patients may present with recurring abdominal pain or hepatomegaly 6
• The most catastrophic presentation is acute hemorrhagic shock from spontaneous rupture, which can be fatal even with aggressive intervention 3, 5
• Hepatic dysfunction may be minimal despite extensive involvement, making clinical detection challenging 2

Associated Etiologies

Anabolic steroid use is the most well-established cause, with the FDA issuing a boxed warning about peliosis hepatis as a serious adverse effect of androgenic anabolic steroid therapy. 2

• The FDA specifically warns that these cysts may be present with minimal hepatic dysfunction but can progress to life-threatening liver failure or intra-abdominal hemorrhage 2
• Withdrawal of anabolic steroids usually results in complete disappearance of the lesions 2
• Other documented associations include thiopurine medications (azathioprine, 6-mercaptopurine, 6-thioguanine), which can cause damage to hepatic vascular endothelium 1
• Additional risk factors include chronic infections, malignancies, immunosuppression, and exposure to certain toxicants, though many cases remain idiopathic 1, 3, 6

Imaging Characteristics

• On CT, peliosis appears as multiple peripheral low-density regions that show early contrast acquisition during the arterial phase and remain isodense with surrounding parenchyma during the late venous phase 6
• Spontaneous high-density foci on non-contrast CT suggest blood components within the cavities 4
• MRI shows hypointense lesions on T1-weighted images and hyperintense on T2-weighted images, with bright foci on all sequences suggesting subacute blood 4
• Angiography demonstrates multiple nodular vascular lesions filling in the parenchymal phase and persisting in the venous phase, consistent with blood-filled cavities 4
• Peliosis can mimic other hepatic lesions including hemangiomas, adenomas, and malignancies on imaging 1, 6

Diagnostic Approach and Critical Pitfalls

Percutaneous liver biopsy is contraindicated when peliosis hepatis is suspected due to the high risk of fatal hemorrhage. 5

• A fatal case report documented hemorrhagic shock and death following diagnostic percutaneous liver biopsy in a patient with unrecognized peliosis 5
• When peliosis is in the differential diagnosis based on imaging characteristics and clinical context (especially anabolic steroid use or thiopurine therapy), surgical resection with diagnostic and therapeutic intent is preferred over biopsy 6
• The condition should be suspected in patients with hypervascular hepatic lesions and relevant medication exposure (anabolic steroids, thiopurines) or risk factors 1, 6, 5
• Thiopurine-induced peliosis should be suspected when patients develop elevated gamma-glutamyl transferase (GGT) and thrombocytopenia, requiring liver biopsy confirmation only when performed safely 1

Management Principles

• Treatment is primarily directed at removing the causative agent (discontinuing anabolic steroids, thiopurines, or other implicated medications) 2, 7, 6
• Most cases are managed conservatively with observation after removal of the offending agent 3, 6
• Hepatic artery embolization has been successfully used as first-line therapy for bleeding peliosis, avoiding the need for operative intervention 7
• Elective surgical resection is appropriate for focal lesions when the diagnosis is uncertain or to prevent future rupture risk 6
• Emergency laparotomy with hemorrhage control is required for ruptured peliosis with hemoperitoneum, though outcomes may be poor despite aggressive intervention 3, 5