Pediatric Cholestatic Syndromes

Generalized Bacterial Infection

Organomegaly with jaundice may be a clinical sign of systemic bacterial infection in the neonate ( Table 63-1 ). The pathogenesis of conjugated hyperbilirubinemia is multifactorial, including the presence of an immature reticuloendothelial system, increased hemolysis, circulating endotoxin, and an immature hepatobiliary system. Although Gram-negative organisms are more commonly reported, both Gram-positive and Gram-negative bacteria can be associated with the development of cholestasis. The natural progression of jaundice associated with Gram-negative neonatal sepsis includes biochemical changes in the first 3 days after the onset of sepsis and resolution that may occur over a variable period and up to 2 months to 3 months after control of the infection. Histologically, the liver shows bile stasis and hepatocellular necrosis. Urinary tract infections, in particular, have frequently been associated with the development of jaundice. Therefore urinalysis and urine culture, along with blood and cerebrospinal fluid cultures (if the infant has fever), should be routinely performed to evaluate infection as a cause of neonatal jaundice. Appropriate infectious monitoring will enable the timely initiation of appropriate antibiotic therapy.

Congenital Syphilis

Congenital syphilis, more common in the developing world, remains a public health issue and should be considered in the differential diagnosis of neonatal cholestasis. Transplacental transmission of Treponema pallidum spirochetes to the fetus may manifest itself phenotypically as a multisystem disease that includes a characteristic diffuse rash, fever, anemia, and aseptic meningitis, in addition to hepatomegaly, increased aminotransferase levels, and jaundice. Histologically, small granulomatous lesions, centrilobular mononuclear infiltration, and widespread portal fibrosis may be seen. Giant cell hepatitis, bile duct paucity, and intrahepatic liver calcifications have been reported. Despite the existence of screening protocols and the availability of a simple, effective, and affordable treatment, most pregnant women worldwide do not receive adequate services. Appropriate serologic testing for syphilis should be undertaken in any infant with unexplained jaundice, especially in endemic regions. If the test is positive, prompt treatment with penicillin should be initiated.

Toxoplasmosis

Maternal infection with the intracellular protozoan Toxoplasma gondii may be asymptomatic or mild in the mother but is a requirement for the development of congenital toxoplasmosis. Although mainly a sequela of primary infection, congenital toxoplasmosis can also occur in infants when women are infected shortly before pregnancy, when immunosuppressed women undergo reactivation, and when women develop a second infection with a different serotype during pregnancy. Infection is mainly acquired by the eating of undercooked meat or from food contaminated with cat feces. Toxoplasmosis transmission leads to a spectrum of clinical manifestations in the infant, with the severity of clinical disease being inversely related to the gestational age at the time of maternal infection. Classic disease with hydrocephalus, chorioretinitis, and intracranial calcifications may not be present at birth, and hepatitis may be the only indication of infection. Liver histology is relatively nonspecific, demonstrating generalized hepatitis with areas of necrosis, intracellular bile stasis, and inflammatory periportal infiltration. However, Toxoplasma organisms may be seen in the liver with use of fluorescent antibody staining.

Prevention of primary toxoplasmosis infection in pregnant women is critical to decreasing the incidence of congenital toxoplasmosis. Prompt treatment of pregnant women at diagnosis of acute toxoplasmosis is recommended to minimize the impact on the offspring. Prenatal diagnosis can be made by the detection of the parasite in fetal blood or amniotic fluid. Postnatally, umbilical cord blood or peripheral blood polymerase chain reaction (PCR) can be used to detect the parasite. If congenital toxoplasmosis is found, treatment of the infant with sulfadiazine and pyrimethamine, in conjunction with folinic acid therapy to prevent hematologic adverse effects, is suggested. Although treatment may prevent further disease progression, it may be ineffective in attacking intracellular organisms or in ameliorating the effects of preexisting tissue damage.

Rubella

Rubella before conception does not present a risk to the fetus; however, when the primary infection occurs during the first trimester, 80% of infants will exhibit symptomatic rubella. Congenital rubella, which manifests itself as heart disease, hepatosplenomegaly, low birth weight, purpura, and cataracts, has become a rare disease because of the rubella vaccine. Congenital rubella is most easily diagnosed with detection of rubella-specific IgM in serum or oral fluid. The virus can be detected by PCR or cultured from blood, urine, cerebrospinal fluid, and throat swabs. Hepatic involvement in congenital rubella is nonspecific, with elevations in conjugated bilirubin, serum aminotransferase, and alkaline phosphatase levels. Liver histology demonstrates marked hepatitis with periportal inflammation and giant cell transformation. Extramedullary hematopoiesis, focal necrosis, and bile duct proliferation can also occur. Treatment of congenital rubella remains largely supportive, and progressive liver disease is rare. Prevention is critical, largely within the context of expanded vaccination programs.

Cytomegalovirus

Cytomegalovirus (CMV) is a common human pathogen with a 45% to 100% worldwide seroprevalence in adults. It is the most common cause of congenital infection, affecting 0.5% to 2% of all live-born infants. Congenital acquisition of CMV may occur transplacentally, at delivery, or postnatally from infected secretions or blood products. Premature infants have been noted to be at increased risk for the development of systemic CMV disease through exposure via breast milk. Most infected infants are asymptomatic (85%), whereas severely affected infants demonstrate the classic syndrome of jaundice, hemolytic anemia, thrombocytopenic purpura, hepatosplenomegaly, and microcephaly with periventricular cerebral calcifications and chorioretinitis. Asymptomatic individuals can develop late-onset complications of their infection within the first 2 years of life, with sensorineural hearing loss being the most common. Liver histology demonstrates giant cell transformation, bile stasis, inflammation, fibrosis, and bile duct proliferation. Intranuclear inclusion bodies in the hepatocyte, bile duct epithelium, or Kupffer cells, along with intracytoplasmic inclusion bodies within the hepatocyte, are characteristic. Positive culture from the urine, nasopharynx, and saliva of affected infants yields the diagnosis; however, newer quantitative PCR assays have demonstrated higher sensitivity and specificity with fewer diagnostic limitations.

Prenatal screening for CMV is currently not recommended given the lack of a proven effective intervention to prevent transmission. However, the use for CMV-specific hyperimmune globulin for the prevention of congenital CMV has shown promise, and larger trials are currently being conducted.

Current treatment strategies for congenital CMV include the use of antiviral drugs such as ganciclovir and foscarnet in combination with CMV immunoglobulin. Although antiviral strategies have been shown to assist in the resolution of the liver disease induced by congenital CMV, the neurologic injury present at birth is usually irreversible.

Herpes Simplex Virus

Typically presenting in a newborn within 28 days after birth, herpes simplex virus (HSV) infection is acquired from the mother in most cases (85% to 90%) at the time of delivery when the infant travels through an infected birth canal, although in utero and postnatal infections can occur. The efficiency of HSV transmission is significantly higher in women who acquire their primary infection near term. Clinical manifestations of neonatal HSV have been divided into three categories: (1) infection confined to the skin, eyes, or mouth without central nervous system or visceral involvement, (2) central nervous system–associated infections, and (3) disseminated infection with multiorgan involvement, including the liver. Clinically, an infant with disseminated HSV will appear normal at birth and within 1 week will develop a presentation indistinguishable from bacterial sepsis with hepatomegaly, jaundice, and temperature instability with progression to shock; fulminant liver failure may be present.

Liver histology reveals extensive areas of necrosis with hemorrhagic changes but minimal inflammation. Characteristic intranuclear inclusions are typically seen at the junction of the normal and necrotic tissue, with prominent giant cell transformation. Importantly, the cutaneous rash often differentiates HSV and varicella-zoster virus infection when a histologically similar appearance can occur. Furthermore, HSV intranuclear inclusions are appreciably smaller than those from CMV infection (see earlier). Diagnosis of disseminated neonatal HSV can be made by detection of the virus by means of qualitative PCR from either the cerebrospinal fluid or plasma. Plasma levels of HSV have been shown to correlate with the clinical presentation and mortality but not with the neurologic outcomes. The use of high-dose antiviral (acyclovir) therapy has dramatically improved the outcomes of children with neonatal HSV; 12-month mortality has been reduced from 85% to 29%. The use of prophylactic antivirals in exposed neonates is currently not recommended because of the relatively low risk of disease and the known adverse effects from the medications. Liver transplant has been used to treat infants with neonatal HSV complicated by acute liver failure.

Enteroviruses

The genus Enterovirus has historically been classified into three main groupings: polioviruses, Coxsackie viruses, and echoviruses. Enteroviruses are known to cause severe fulminant hepatic failure with the Coxsackie B viruses and echoviruses being the most commonly reported. Clinical presentation is generally nonspecific, with poor feeding, lethargy, jaundice, temperature instability, and rash. Disseminated intravascular coagulation and progressive hepatic failure can occur. A maternal history of prodromal viral symptoms may be elicited. These infections may be severe, with liver histology showing acute hepatic necrosis. Infant mortality can be as high as 83%, and survivors can demonstrate persistent hepatic dysfunction. Diagnosis can be made by virus particle detection from blood, stool, urine, or another affected site. PCR is more commonly used over culture given its superior sensitivity and shorter result time.

Supportive care remains the mainstay of treatment; although no virus-specific therapy is used, ongoing research focuses on the development of more enterovirus-specific immune globulin as well as directed antiviral therapies targeted at known enterovirus antigens. Intravenous immunoglobulin has been used to treat severe cases given its broad antiviral properties.

Parvovirus B19

Parvovirus B19 infection should be included in the differential diagnosis of infants with cholestasis in the newborn period. Parvovirus B19 infection usually manifests itself as a mild, self-limited systemic disease classically associated with the “slapped cheek” facial rash. However, it has been reported to cause a spectrum of liver disease ranging from mild hepatitis with cholestasis to fulminant hepatic disease associated with aplastic anemia. Laboratory diagnosis consists of IgM antibody testing. Treatment with monoclonal anti-CD52 antibodies has demonstrated some success.

Varicella-Zoster Virus

Varicella-zoster virus is a member of the herpes virus family whose primary infection is known to cause chickenpox. Complications from acquired varicella-zoster virus infection in the first 6 months of life are rare because of circulating maternal antibodies. However, hepatic complications from varicella-zoster virus infection have been reported, with 1.9% of infants infected with varicella-zoster virus manifesting some degree of hepatic involvement. Treatment is mainly supportive unless an absence of maternal immunity is demonstrated, in which case antiviral therapy should be initiated.

Hepatotropic Viruses

There are few data to suggest that any of the known hepatitis viruses (A, B, C, D, and E) are causative agents of cholestasis in the neonatal period, and routine screening in infants presenting with jaundice is not necessary.

Biochemistry and Genetics

A1AT is a secreted glycoprotein produced predominantly by the liver. Functionally, A1AT can be classified as a protease inhibitor (Pi) targeting neutrophil elastase in addition to several other neutrophil proteinases with substantial tissue activity. More than 100 allelic variants, designated as Pi phenotypes and inherited in a dominant fashion, have been identified. Structural variants are classified by agarose gel electrophoresis, in which a letter is assigned to each A1AT variant according to the position of gel migration. The most common A1AT variant in the United States is the M family; thus the normal phenotype is PiMM with corresponding A1AT serum concentrations greater than 1.5 g/L. Individuals with the most common severe deficiency variant have an A1AT mutant protein that migrates on the gel to a location designated Z. Individuals with the PiZZ phenotype produce a protein that is retained in the hepatocyte, with minimal secretion into the circulation ( Table 63-2 ). Although most of the mutant protein undergoes degradation by proteosomal and autophagic processing, some of the protein escapes this process and accumulates and aggregates in hepatocytes. The disease associated with A1AT deficiency represents a toxic gain of function in which the mutant protein incites a series of cytotoxic injuries. Only a minority (8% to 10%) of PiZZ homozygotes develop hepatic manifestations, suggesting that there exist additional to-be-determined genetic or environmental factors unique to those individuals who present with significant liver disease early in life. Although PiZZ is recognized as the most common phenotype of children with liver disease, several other allelic variants have been reported to affect the liver in a manner similar to PiZZ children. Individuals with the compound heterozygosity PiSZ phenotype may demonstrate a liver injury pattern analogous to PiZZ. Liver disease has also been reported in patients with several other A1AT allelic variants, such as PiM _malton , PiM _W , PiM _Duarte , and Pi _FZ .

Clinical Manifestations and Outcomes of α ₁ -Antitrypsin Deficiency–Associated Liver Disease

The presentation of children with liver involvement secondary to A1AT deficiency is bimodal with (1) early presentation of cholestasis (within the first 1 month to 2 months of life) and (2) older children presenting with advanced, chronic disease manifesting itself as portal hypertension, hematemesis, or cryptogenic cirrhosis. Laboratory investigations in A1AT-deficient infants with jaundice typically show elevated conjugated bilirubin and serum aminotransferase, alkaline phosphatase, and γ-glutamyltransferase (GGT) levels. Decreased birth weights unrelated to prematurity may also be seen. Children may present with variable degrees of liver failure, even early in the course.

The natural history of A1AT deficiency–associated liver disease is best described in the Swedish nationwide screening study, where multiple outcome patterns were appreciated. Of 200,000 infants screened, 120 were identified as having PiZZ; 14 of the 120 had prolonged jaundice, with 9 having severer liver complications. Eight of the 120 children with PiZZ were noted to have mild hepatic involvement with slightly elevated bilirubin and aminotransferase levels. Approximately 50% of the remaining PiZZ children were noted to have abnormal aminotransferase levels. Recent prospective studies have demonstrated that many A1AT-deficiency children who present with hepatic involvement spontaneously improve. Factors that promote progression of liver disease secondary to A1AT deficiency are largely unknown.

Hepatic Pathology

The distinctive histologic finding of homozygous PiZZ A1AT deficiency is the presence of periodic acid–Schiff-positive, diastase-resistant eosinophilic globules in the endoplasmic reticulum of affected livers ( Fig. 63-2, A ). However, the presence of these globules is not diagnostic, as similar lesions have been shown in individuals with the PiMM phenotype and alternative hepatic disease processes. Less specific findings include hepatocellular damage with giant cell transformation, portal fibrosis, and both bile duct proliferation and paucity.

Diagnosis

Diagnosis is best achieved by determination of the A1AT phenotype by isoelectric focusing or by agarose gel electrophoresis at an acidic pH. Serum levels of A1AT are not reliable for diagnostic purposes as various clinical scenarios can affect the level. Low levels have been found in PiMM infants born prematurely, and as an acute-phase reactant, A1AT levels may be falsely elevated in states of inflammation or stress. A diagnosis of A1AT deficiency–associated liver disease in heterozygote infants (PiMZ, PiMS, or PiSZ) should be made cautiously. Although investigators have aimed to demonstrate an association between phenotype and disease burden, the population studied was drawn form a pathology registry and concurrent prospective controls were not included.

Treatment

Currently, there is no specific therapy for A1AT deficiency–associated liver disease. Appropriate supportive care with nutritional and vitamin replacement while cholestasis persists is important. Liver transplant has been performed in children with progressive dysfunction, with transplantation allowing for excellent survival in children and adults. However, as the autophagic and genetic contributions to disease pathogenesis are becoming clearer, newer disease strategies are emerging. Autophagy is a process by which cells self-digest and recycle amino acids as a mechanism for homeostatic turnover and to survive stresses such as starvation. Autophagy-enhancing drugs, such as carbamazepine, have been shown to decrease hepatic A1AT accumulation. Additional therapeutic strategies on the horizon include gene therapy and autologous cell–based therapies.

Clinical Manifestations and Hepatic Pathology

CFALD is usually asymptomatic and slowly progressive, and the diagnosis is made when patients develop organomegaly, portal hypertension, or variceal bleeding. A minority of patients will present with a clinical picture of neonatal cholestasis. For the vast majority, resolution of jaundice is expected during the first few months of life. Liver biopsies may show steatosis (23% to 67% of patients), possibly related to nutritional deficiencies, and focal biliary cirrhosis with areas of portal inflammation and fibrosis, bile duct obstruction and proliferation, and the inclusion of eosinophilic material in the bile ductules are characteristic (see Fig. 63-2, B ). Significant disease has been detected in 11% of infants and up to 72% of adults. Focal biliary cirrhosis may progress to severe multilobular cirrhosis with portal hypertension or liver failure.

Diagnosis

The diagnosis of CFALD is usually established by a combination of physical findings, biochemical tests, imaging techniques, and histology. The patient may have hepatomegaly (steatosis) or a small, hard, or multilobulated liver (cirrhosis), splenomegaly, palmar erythema, spider nevi, and clubbing. Among the liver enzymes, GGT may be particularly helpful. Given its improved sensitivity over biochemical testing, ultrasonography should be performed in any child with suspected CFALD. Additional imaging modalities that have been used in the evaluation of CFALD are CT, MRI, and magnetic resonance cholangiopancreatography; transient elastography (FibroScan) and acoustic radiation force impulse imaging have shown promise for their usefulness in detecting significant CFALD. Liver biopsy remains the gold standard for the diagnosis of many chronic liver diseases, but the benign nature of fat infiltration in cystic fibrosis–related steatosis and the uneven distribution of lesions in focal biliary cirrhosis makes pursuit of histologic assessment in patients with cystic fibrosis controversial.