Pediatric Cholestatic Liver Disease



Pediatric Cholestatic Liver Disease


Marcela Salomao, MD



14.1 INTRODUCTION

Pediatric cholestatic liver diseases are a heterogeneous group of illnesses, including infections, metabolic disorders, congenital malformations, and many others.1 Liver biopsy interpretation is challenging because major histologic findings commonly overlap and clinicopathologic correlation is almost always required for a final diagnosis. (Fig. 14.1). This chapter will provide a pattern recognition-based approach to describe pediatric diseases associated with cholestasis, with an emphasis on key histopathologic features and common diagnostic pitfalls.


14.2 BILIARY ATRESIA


Introduction

Biliary atresia is an inflammatory and fibrosing disease of extrahepatic bile ducts and represents an important cause of neonatal cholestasis. Early diagnosis is crucial to prevent progression to biliary cirrhosis. Biliary atresia cases are almost always treated with hepatoportoenterostomy (or Kasai procedure), a technique named after its creator, surgeon Morio Kasai, that aims at restoring the bile flow to the small bowel, hence slowing progression to cirrhosis.2 The procedure yields variable results, with most patients progressing to biliary cirrhosis and ultimately requiring liver transplantation.3 In fact, biliary atresia is the most common indication for liver transplantation in pediatric patients.

Liver biopsy evaluation plays a key role in the diagnosis of biliary atresia. Awareness about the early changes in the disease and the possible pitfalls is critical in the histologic evaluation of these cases.


Epidemiology

In the United States, biliary atresia occurs at a frequency of 1 in 15,000 live births with seasonal clustering of the disease and higher rates in nonwhite infants.4 European and Asian studies have demonstrated rates ranging from 1:6,000 in Taiwan to 1:20,000 live births in France, but no seasonal variation was identified.5, 6, 7 Female gender, advanced maternal age, and multiparity are associated with slightly increased
risk for the disease.8,9 Splenic malformation and other syndromic features are present in about 10% of cases. Reports of familial biliary atresia are exceptionally rare10 and studies of twin infants showed discordance of presentation.11,12






Figure 14.1 Differential diagnosis and key histologic features of cholestasis in neonates and older children.


Classification

Biliary atresia can be broadly classified as nonsyndromic (or perinatal), syndromic (or embryonic), and cystic. Nonsyndromic biliary atresia accounts for 80% of cases and is not typically associated with other malformations. Syndromic biliary atresia represents about 10% of cases and encompasses a heterogeneous group of patients, who present with early onset jaundice and, many times, absent extrahepatic biliary tree. Macroscopic splenic malformations are classically described in syndromic biliary atresia, a condition named biliary atresia-splenic malformation syndrome. Biliary atresia-splenic malformation syndrome typically occurs together with other malformations, including situs inversus, intestinal malrotations, portal vein anomalies, and cardiac defects. The syndrome occurs more frequently in females, has a higher association with maternal diabetes, and has a worse outcome following Kasai procedure.13,14 Syndromic cases are often referred to as “early” or “embryonic” forms and nonsyndromic biliary atresia as “late” or “perinatal,” presuming that timing of disease in syndromic cases is different than nonsyndromic biliary atresia. More recent studies have demonstrated that this temporal classification may be too simplistic and therefore should be avoided until studies with better definitions and better group homogeneity are made available.15 The cystic variant of biliary atresia represents 8% of patients and is characterized by cystic dilatation of the atretic biliary remnants. Some cases can be detected prenatally, and jaundice may occur early or late. Cystic biliary atresia appears to have a better prognosis than syndromic and nonsyndromic cases.16



Etiology and pathogenesis

Biliary atresia is a multifactorial disease, and its exact etiology remains unclear. Recent studies suggest that developmental, environmental, and immune elements play a role in the disease. Infectious etiologies have been proposed but never confirmed, whereas the clustering of biliary atresia cases in Australia livestock suggests that toxins can lead to the development of disease.17,18 Mutations in the CFC1 gene have been associated with biliary atresia-splenic malformation cases.19


Clinical presentation

Jaundice is the first and most important manifestation of biliary atresia, occurring anywhere from birth to 8 weeks of age. In most cases, infants are born at full term and are healthy in the first weeks of life. Acholic stools and dark urine may be present, but are often unrecognized by parents. Patients who present later in the course of disease often have hepatosplenomegaly. Conjugated hyperbilirubinemia (>2 mg/dL) and extremely high levels of γ-glutamyl transpeptidase (GGT) are typical. Recent studies show that conjugated bilirubin levels are slightly elevated in the asymptomatic early stages of disease and suggest that serum bilirubin concentrations or stool color cards can be useful as newborn screening tools.20


Imaging findings

When the diagnosis of biliary atresia is suspected, abdominal ultrasound is performed to rule out anatomical anomalies, such as choledochal cysts, polycystic liver/kidney disease, Caroli disease, and tumors. In biliary atresia, ultrasonographic evaluation demonstrates an absent or abnormal gallbladder. When present, portal hypertension can usually be identified on ultrasound. Other possible findings include an absent common bile duct, the “triangular cord” sign (triangular echogenic density present immediately above the porta hepatis), and an abnormal gallbladder shape.21

Following abdominal ultrasound, hepatobiliary scintigraphy is performed to evaluate the patency of the extrahepatic biliary tree using a technetium-labeled iminodiacetic acid analogous compound as a marker. Absent excretion of the marker into the bowel strongly supports the diagnosis of biliary atresia. This test is found to be 100% sensitive and 93% specific when patients are pretreated with phenobarbital.22 Magnetic resonance cholangiography is another imaging modality of high diagnostic accuracy.23

Liver biopsy is performed in nearly all infants with suspected biliary atresia. The main purpose of the biopsy is to confirm the diagnosis of biliary tract obstruction by histology and to exclude diseases that may mimic biliary atresia. Following scans and liver biopsy, patients undergo intraoperative cholangiogram, the gold standard for the diagnosis of biliary atresia. The presence of biliary obstruction on intraoperative cholangiogram confirms the diagnosis of biliary atresia and is usually followed by hepatoportoenterostomy at the time of examination.


Histopathologic features

On liver biopsies, the histologic findings of biliary atresia are not entirely specific, requiring correlation with clinical and laboratorial findings. Microscopically, there is marked cholestasis in the form of canalicular, hepatocellular, and ductular bile accumulation. Features of large bile duct obstruction are almost always present, including portal edema, fibrosis, and ductular proliferation (Figs. 14.2 and 14.3). Mild neutrophilic infiltrates typically accompany the proliferating bile ductules. In addition, the lobular parenchyma may show centrilobular hepatocyte swelling with or without features of cholate stasis, namely periportal hepatocellular swelling, cytoplasmic rarefaction, and Mallory-Denk bodies. Periportal accumulation of copper-binding protein is sometimes present. Extramedullary hematopoiesis is often seen and needs to be differentiated from inflammation. The presence of significant inflammation, apoptosis, or confluent necrosis should raise the possibility of an alternative diagnosis, such as neonatal hepatitis (Table 14.1). Giant cell transformation of hepatocytes, a feature classically described in neonatal hepatitis, can occur in biliary atresia (Fig. 14.2). Liver biopsies performed at earlier stages will demonstrate less conspicuous findings and may be harder to differentiate from other processes (Fig. 14.4). Later, portal-based fibrosis
can progress to bridging and nodularity. The loss of native bile ducts also occurs in the later stages of disease.24 Occasionally, bile duct plate malformations may be present and have been reported to predict a worse clinical outcome.25






Figure 14.2 Biliary atresia. Portal tracts are expanded by fibrosis and ductular proliferation. Note multinucleated giant hepatocytes (upper center; lower center).






Figure 14.3 Biliary atresia. Masson-trichrome stain demonstrates extensive bridging fibrosis in a 16-week-old patient.








Table 14.1 Clinical and histopathologic features of biliary atresia and neonatal hepatitis syndrome








































Histology


Biliary atresia


Neonatal hepatitis



Ductular proliferation


Lobular inflammation



Portal-based fibrosis


Confluent necrosis



Absence of lobular inflammation/apoptosis




Absence of confluent necrosis



Clinical Features


Elevated GGT


GGT normal or mildly elevated


Nonexcreting IDA scan


Normal imaging of biliary tree


Normal A1AT phenotype



No history of TPN



Abbreviations: A1AT, α-1-antitrypsin; GGT, γ-glutamyl transpeptidase; IDA, technetium-labeled diisopropyl iminodiacetic acid; TPN, total parenteral nutrition.


Typically, a Kasai procedure is performed at the time of intraoperative cholangiogram. In this procedure, a loop of small intestine is anastomosed to the hepatic hilum, after the biliary remnant and portal fibrous plate have been resected. The resected specimen that results from a Kasai procedure consists of a fibrotic/atrophic segment of the extrahepatic bile duct (Fig. 14.5). Proper orientation of the specimen by the surgeon and the pathologist is a key step in the evaluation of a Kasai specimen. The proximal aspect of the specimen contains the portal plate and surrounding liver parenchyma. Distally, the specimen contains a segment of common hepatic duct, the cystic duct, and gallbladder, and finally a segment of common bile duct. The gallbladder is typically smaller than normal and might not have a lumen. Sampling should include the portal plate and consecutive sections of the extrahepatic biliary tree, including the gallbladder remnant. Sections of the atretic bile duct demonstrate partial to total luminal occlusion by fibrosis and variable inflammation (Fig. 14.6). Evaluation of the portal plate is recommended because the presence of large-caliber bile ducts (150 to 200 µm) within the portal plate is associated with a better clinical prognosis, while
scant small bile ducts in the portal plate sections are associated with a worse prognosis and lower survival (Fig. 14.7).26,27,28






Figure 14.4 Biliary atresia. At earlier stages, cholestasis and minimal portal changes may be the only findings. This biopsy was obtained at 9 weeks of age.






Figure 14.5 Kasai specimen. The components of a Kasai specimen that should be sampled for microscopic examination.






Figure 14.6 Kasai specimen. Cross-section of partially occluded bile duct with fibrosis, chronic inflammation and inspissated luminal bile.

Explant specimens from patients who have failed a Kasai procedure and proceeded to liver transplantation will show a shrunken and cirrhotic liver with the typical features of biliary cirrhosis. Histologically, incomplete nodule formation can confer a “geographic” appearance. Features of large bile duct obstruction are present throughout the specimen. At this stage, inflammation, injury, and loss of interlobular bile ducts may be present. Prolonged cholestasis will result in cholate stasis. Extramedullary hematopoiesis and giant multinucleated hepatocytes are less common, unless liver transplantation occurs at an early stage of disease. Hepatocellular carcinoma is a rare complication, reported in less than 1% of biliary atresia patients.29 Large regenerative nodules are described in patients that have undergone Kasai procedure and may mimic hepatocellular neoplasms.30






Figure 14.7 Kasai specimen. Sampling of hepatic plate will demonstrate the degree of bile duct patency. In this example, denuded medium-sized bile ducts are present.




14.3 NEONATAL HEPATITIS

Neonatal hepatitis syndrome is a cholestatic syndrome characterized by hepatocellular injury occurring in the neonatal period. A number of possible etiologies has been associated with the neonatal hepatitis pattern, including infections, inborn errors of metabolism, anatomical defects, and many others (Table 14.2). Among infectious etiologies, TORCH infections, especially Cytomegalovirus, remain an important
cause.34 Other considerations include sepsis (Escherichia coli) and other viral processes (Coxsackievirus, Echovirus, Herpesvirus, and Adenovirus). The syndrome is more commonly described in male infants and is associated with prematurity and low-birth weight.35 Clinically, not all patients will have noticeable jaundice, but conjugated hyperbilirubinemia is consistently present.








Table 14.2 Etiology of neonatal hepatitis




















Infections



TORCH infections (congenital Toxoplasmosis, Others such as syphilis, varicella-zoster, parvovirus B19, Rubella, Cytomegalovirus, Herpes simplex), viral hepatitis B and C, HHV-6, HIV, bacterial infections, listeria, and tuberculosis


Metabolic disorders



α-1-Antitrypsin deficiency, galactosemia, tyrosinemia, fructosemia, glycogen storage disorder type IV, Niemann-Pick disease Types A and C, Gaucher disease, Wolman disease, inborn errors of bile acid metabolism, Zellweger syndrome, citrullinemia Type II, mitochondrial DNA depletion syndrome, panhypopituitarism, hypothyroidism, and Dubin-Johnson syndrome


Immune-mediated diseases



ABO incompatibility, neonatal lupus erythematosus, and neonatal hepatitis with neonatal hemolytic anemia


Idiopathic


When evaluating a liver biopsy, it is key to exclude biliary atresia as this distinction directly affects patient management and outcome.

Histologically, neonatal hepatitis is characterized by cholestasis, prominent giant cell transformation of hepatocytes, and extramedullary hematopoiesis (Figs. 14.8 and 14.9). Portal and lobular inflammation and lobular apoptosis are helpful diagnostic findings, but are not always present (Fig. 14.10). Portal tracts may have inflammation and mild fibrosis. Significant ductular proliferation and advanced fibrosis are typically absent. Small, “hypoplastic” interlobular bile ducts were described in about one-third of cases and can be easily mistaken for ductopenia.36 CK7 immunohistochemistry is useful in delineating native bile ducts and ductular proliferation. A minority of cases show massive/submassive necrosis, characterized by extensive parenchymal loss and collapse of the reticulin framework, in a pattern most commonly associated with gestational alloimmune disease (neonatal hemochromatosis, see
Chapter 17), viral hepatitis B and certain metabolic disorders. A diligent search for viral cytopathic effect is important in identifying infectious hepatitis, and immunohistochemical studies may be useful in this setting.






Figure 14.8 Neonatal hepatitis. Prominent giant cell transformation of hepatocytes and extramedullary erythropoiesis.






Figure 14.9 Neonatal hepatitis. Multinucleated giant hepatocytes predominate in this centrilobular region. Note the lack of significant ductular proliferation and portal fibrosis.






Figure 14.10 Neonatal hepatitis. Lobular inflammation and apoptosis.

Following a histologic diagnosis of neonatal hepatitis, patients usually undergo further testing. Patients found to have viral diseases may benefit from antiviral therapy, whereas cases of tyrosinemia, defects in bile acid synthesis, and hypopituitarism can be managed with appropriate pharmacotherapy. Idiopathic neonatal hepatitis still accounts for 25% of cases.34,37,38 Higher mortality rates are seen in patients with severe inflammation in the biopsy, prolonged jaundice, acholic stools, familial disease, and unremitting hepatosplenomegaly.39


14.4 PAUCITY OF INTRAHEPATIC BILE DUCTS


Syndromic paucity of intrahepatic bile ducts (Alagille syndrome)

As described by Alagille and colleagues,40,41 this disease, also known as arteriohepatic dysplasia, is characterized by bile duct loss, cholestatic liver injury, and distinct extrahepatic malformations, including congenital heart disease, dysmorphic facies (inverted triangle with broad forehead and pointy chin, mild hypertelorism, and deep-set eyes), posterior embryotoxon in the eye, butterfly-shaped vertebrae, and renal abnormalities.42,43 Nonsyndromic cases are also described and include a vast number of diseases discussed later in this chapter.

Only gold members can continue reading. Log In or Register to continue

Stay updated, free articles. Join our Telegram channel

Oct 16, 2018 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Pediatric Cholestatic Liver Disease

Full access? Get Clinical Tree

Get Clinical Tree app for offline access