Peliosis hepatis overview
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# Overview
Peliosis Hepatis is an uncommon vascular condition characterised by randomly distributed multiple blood-filled cavities throughout liver. Size of the cavities usually ranges between a few millimetres to 3 cm in diameter. In the past it was a mere histological curiosity  occasionally found at autopsies but has been increasingly recognised with wide ranging conditions from AIDS to the use of anabolic steroids. It also occasionally affects spleen, lymph nodes, lungs, kidneys, adrenal glands, bone marrow and other parts of gastrointestinal tract..
Peliosis hepatis is often erroneously written "peliosis hepatitis", despite its not being one of the hepatitides.  The correct term arises from the Greek pelios, i.e. discoloured by extravasated blood, livid, and the Latinized Genitive case (hepatis) of the Greek hepar, liver.

# Historical Perspective
There is limited information about the historical perspective of Peliosis hepatis

# Classification
There is no established system for the classification of Peliosis hepatis

# Pathophysiology
The pathogenesis of peliosis hepatis is unknown. There are several hypotheses, such as, it arise from sinusoidal epithelial damage, increased sinusoidal pressure due to obstruction in blood outflow from the liver, or hepatocellular necrosis.
Two morphologic patterns of hepatic peliosis were described by Yanoff and Rawson . In the phlebectatic type, the blood-filled spaces are lined with endothelium and are associated with aneurismal dilatation of the central vein; in the parenchymal type, the spaces have no endothelial lining and they usually are associated with haemorrhagic parenchymal necrosis. Some considers both pattern to be one process, initiated by focal necrosis of liver parenchyma observed in parenchymal type progressing into formation of fibrous wall and endothelial lining around haemorrhage of phebectatic type. Fibrosis, cirrhosis, regenerative nodules, and tumours may also be seen.

# Causes
Peliosis hepatis may be caused by drugs, toxins, chronic wasting disease, malignancy, and infection. Peliosis Hepatitis may develop in individuals with renal or cardiac transplantation, but in about 20-50% of patients, they are no comorbidities.
common causes include
- Corticosteriods
- Oral Contraceptives
- Tuberculosis
- Malignancy particularly Hepatocellular Carcinoma
- Diabetes mellitus
- Necrotizing vasculitis
- Infection in AIDS, bacillary peliosis caused by Bartonella henselae and Bartonella quintana)
- Hematologic disorders. 

# Differentiating Peliosis hepatis from Other Diseases
Peliosis hepatis must be differentiated from Hepatic Adenoma, Hemangioma, Focal Nodular Hyperplasia, Hepatic Abscess, Hypervascular Metastases, and Hepatocellular Carcinoma. Polycystic liver disease, Congenital hepatic fibrosis, Solitary congenital cysts, Hydatid cyst, Von Meyenburg complexes, Caroli disease (type V choledochal cyst).

# Epidemiology and Demographics
The prevalence of Peliosis hepatis is approximately 0.2 percent of patients with pulmonary tuberculosis and about 22 percent in patients following renal transplant. It is most commonly associated with renal transplants.

## Physical Examination
The condition is typically asymptomatic and is discovered following evaluation of abnormal liver function test. However, when severe it can manifest as jaundice, hepatomegaly, liver failure and haemoperitoneum.

## Laboratory Findings
There are no diagnostic laboratory findings associated with Peliosis Hepatis

## Imaging Findings
Ultrasound appears non-specific, usually demonstrating an irregular hypoechoic region or mass, and on Computerized Tomography (CT scan) shows multiple hypoattenuating lesions of variable size. Central bleeding may lead to areas of hyperattenuating and even dystrophic calcification. Magnetic resonance imaging (MRI) may typically show hypointense, hyperintense, or enhancement, usually centrifugal (from the center outward). Angiography may  show hypervascularity with multiple vascular nodules. 

## Other Diagnostic Studies
There are no other diagnostic studies associated with Peliosis Hepatis

# Treatment

## Medical Therapy
- Bacillary peliosis hepatitis (peliosis hepatis caused by Bartonella spp.)
- Preferred regimen (1): Clarithromycin 500 mg bid for 4 months
- Preferred regimen (6): Erythromycin 500 mg PO qid for 4 months
- Preferred regimen (2): Doxycycline 100 mg PO bid for 4 months
- Special Consideration
- Severe disease
- Preferred regimen: Doxycycline 100 mg PO/IV bid for 4 months AND Rifampin  300 mg PO bid for 4 months

## Surgery

## Prevention

# See Also
- Polycystic Liver Disease
- Solitary congenital cysts
- Congenital hepatic fibrosis
- Hydatid cyst
- Von Meyenburg complexes
- Caroli disease (type V choledochal cyst)
- Type IV choledochal cysts