**5. Early post-transplant liver enzyme abnormalities**

The differential diagnosis of liver enzyme abnormalities varies with the amount of time which has passed since liver transplant. In the normal post-transplant course, liver enzymes typically rise immediately following transplant and become normal or near-normal within 3-5 days. If the enzymes fail to improve or normalize but soon rise again, it is likely that an early complication has occurred (Table 1). In the very early post-transplant period (within the first week), liver enzyme abnormalities can be related to primary graft nonfunction (PNF) or dysfunction, hepatic arterial insufficiency, small for size syndrome (SFSS), or portal venous thrombosis (PVT).

#### **5.1. Primary graft dysfunction**

PNF and primary graft dysfunction are associated with prolonged ischemia time [15], and it is likely that preservation and reperfusion injury play a role. PNF is heralded by a precipi‐ tous rise in hepatic transaminases in the second or third postoperative day accompanied by signs of hepatic failure (encephalopathy and coagulopathy). Once hepatic artery thrombosis (HAT) has been ruled out by imaging, a liver biopsy confirms the diagnosis. Biopsies in this setting typically show centrilobular hepatocyte dropout due to hepatocellular necrosis, with compensatory zone 2 hepatocyte proliferation and bile ductular proliferation [16].

#### **5.2. Hepatic artery thrombosis**

The clinical presentation of HAT is quite similar to that of PNF, with a dramatic increase in hepatic transaminases and bilirubin in the very early post-transplant period. A liver biopsy is typically not required, as the diagnosis can usually be confirmed with angiography. When performed, biopsies of patients with hepatic arterial insufficiency show hepatocyte foamy degeneration or necrosis and features of ischemic cholangitis [17].

**5.3. Portal vein thrombosis**

**5.4. Small for size syndrome**

**5.5. Acute cellular rejection**

firm response to treatment.

complications (Table 2).

**5.6. Late post-transplant liver enzyme abnormalities**

Early acute PVT presents clinically as acute hepatic failure and demonstrates histological features of hepatocyte necrosis. Occasionally, PVT presents later, in which case the features of portal hypertension dominate. In this situation, if a biopsy is performed, it can be normal

Liver Biopsy After Liver Transplantation http://dx.doi.org/10.5772/52617 193

Patients with SFSS present with dominant features of portal hypertension, such as ascites and variceal bleeding. This syndrome is the result of relative portal hyperperfusion com‐ pared to hepatic arterial blood flow, and often occurs when the transplanted liver (or liver segment) is less than 0.6- 0.8% of the recipient body weight [20,21]. The diagnosis is typically made clinically, with signs of portal hypertension such as ascites and variceal bleeding. If a liver biopsy is performed, the allograft typically shows centrilobular cholestasis, centrilobu‐

The most common cause of early allograft dysfunction is acute cellular rejection (ACR). Although most cases of ACR occur in the first three months post-transplant (most often in the second or third post-transplant week), late-onset ACR (occurring up to 10 years post-transplant) has been reported [23]. ACR typically presents as moderate to severe el‐ evations in hepatic transaminases and alkaline phosphatase/GGT, with some degree of bilirubin elevation, often in patients with a recent history of inadequate immunosuppres‐ sion. The "gold standard" for the diagnosis of ACR remains the liver biopsy, which typi‐ cally shows variable degrees of mixed portal inflammation (often with increased eosinophils), bile duct inflammation, and endotheliitis (typically in the portal vein or cen‐ tral vein branches) (Figure 1). The Banff criteria are the most widely used to describe ACR, and give a score of 1-3 for each component. These scores are added to calculate the Rejection Activity Index (RAI), which ranges from 3-4 (mild ACR) up to greater than 7 (severe ACR) [24]. It should be noted that late-onset ACR often appears quite different histologically, with a greater likelihood of lobular inflammation, less prominent bile duct inflammation, and a tendency towards monotypic portal inflammation [25]. A follow-up liver biopsy after 3-7 days of increased immunosuppression is occasionally used to con‐

Beyond three months post-transplant, the differential of liver enzyme abnormalities changes. Broadly, the diagnoses can be categorized as chronic rejection, native disease recur‐ rence, de novo infectious complications, toxic complications, de novo hepatitis, or vascular

or show features of nodular regenerative hyperplasia [18,19].

lar steatosis, and interface ductular proliferation [22].


**Table 1.** Differential diagnosis of early post-transplant liver enzyme abnormalities

#### **5.3. Portal vein thrombosis**

performed, biopsies of patients with hepatic arterial insufficiency show hepatocyte foamy

bilirubin, INR. Encephalopathy in severe injury

Severe elevation of transaminases, bilirubin, alkaline phosphatase/GGT

Elevated transaminases, bilirubin, alkaline phosphatase. Possible recent history of inadequate immunosuppression

Early: acute hepatic failure Late: ascites, variceal bleeding

Ascites, spontaneous bacterial peritonitis, variceal bleeding

Within 3 days Elevated transaminases,

**Clinical presentation Risk Factors Histological**

Prolonged cold or warm ischemia time, greater than 30% donor steatosis

Technical/anastomotic complications

Younger recipient, older donor, history of autoimmune disorder, ? female recipient [17]

Hypercoagulable state, prior history of PVT

Graft-to-recipient body weight ratio less than 0.6 [18, 19]

**Characteristics**

Centrilobular hepatocyte dropout, zone 2 hepatocyte proliferation, bile duct proliferation [16]

Foamy hepatocyte degeneration, features of ischemic cholangitis

Portal inflammation, biliary inflammation, endothelitis

Often normal, may show features of focal nodular hyperplasia [21, 22]

Centrilobular cholestasis and steatosis, interface bile duct inflammation [20]

degeneration or necrosis and features of ischemic cholangitis [17].

**presentation**

Day 2 to 7 posttransplant

Typically 2-3 weeks after transplant, up to 3 months posttransplant

week posttransplant Late: within first year posttransplant

Sequelae of portal hypertension: 6 to 12 months post-transplant

**Table 1.** Differential diagnosis of early post-transplant liver enzyme abnormalities

Less than 1% Early: within first

**Incidence Time of**

Up to 30% (2-7% severe) [15]

192 Liver Biopsy - Indications, Procedures, Results

3-10% in adult transplant (up to 40% in pediatric transplant) [17]

24-80% by 6 months posttransplant [26]

Not well defined, but greatest when graft-torecipient body weight ratio is less than 0.6 [18]

Disease/ Complication

Preservation/ Reperfusion Injury

Hepatic artery thrombosis

Acute Cellular Rejection

Portal vein thrombosis

Small for size syndrome

Early acute PVT presents clinically as acute hepatic failure and demonstrates histological features of hepatocyte necrosis. Occasionally, PVT presents later, in which case the features of portal hypertension dominate. In this situation, if a biopsy is performed, it can be normal or show features of nodular regenerative hyperplasia [18,19].

#### **5.4. Small for size syndrome**

Patients with SFSS present with dominant features of portal hypertension, such as ascites and variceal bleeding. This syndrome is the result of relative portal hyperperfusion com‐ pared to hepatic arterial blood flow, and often occurs when the transplanted liver (or liver segment) is less than 0.6- 0.8% of the recipient body weight [20,21]. The diagnosis is typically made clinically, with signs of portal hypertension such as ascites and variceal bleeding. If a liver biopsy is performed, the allograft typically shows centrilobular cholestasis, centrilobu‐ lar steatosis, and interface ductular proliferation [22].

#### **5.5. Acute cellular rejection**

The most common cause of early allograft dysfunction is acute cellular rejection (ACR). Although most cases of ACR occur in the first three months post-transplant (most often in the second or third post-transplant week), late-onset ACR (occurring up to 10 years post-transplant) has been reported [23]. ACR typically presents as moderate to severe el‐ evations in hepatic transaminases and alkaline phosphatase/GGT, with some degree of bilirubin elevation, often in patients with a recent history of inadequate immunosuppres‐ sion. The "gold standard" for the diagnosis of ACR remains the liver biopsy, which typi‐ cally shows variable degrees of mixed portal inflammation (often with increased eosinophils), bile duct inflammation, and endotheliitis (typically in the portal vein or cen‐ tral vein branches) (Figure 1). The Banff criteria are the most widely used to describe ACR, and give a score of 1-3 for each component. These scores are added to calculate the Rejection Activity Index (RAI), which ranges from 3-4 (mild ACR) up to greater than 7 (severe ACR) [24]. It should be noted that late-onset ACR often appears quite different histologically, with a greater likelihood of lobular inflammation, less prominent bile duct inflammation, and a tendency towards monotypic portal inflammation [25]. A follow-up liver biopsy after 3-7 days of increased immunosuppression is occasionally used to con‐ firm response to treatment.

#### **5.6. Late post-transplant liver enzyme abnormalities**

Beyond three months post-transplant, the differential of liver enzyme abnormalities changes. Broadly, the diagnoses can be categorized as chronic rejection, native disease recur‐ rence, de novo infectious complications, toxic complications, de novo hepatitis, or vascular complications (Table 2).

Disease/ Complication **Incidence Time of**

Chronic rejection 3-5% 3-12 months after

Recurrent HCV Near-universal Re-infection

Recurrent HBV Less than 10%

CMV infection 5-8% with

EBV infection Up to 80% of

with adequate prophylaxis [36]

prophylaxis

patients who are EBV-antibodynegative at time of transplant

**presentation**

transplant

within 72 hours; histological recurrence within 1-2 weeks; clinically significant recurrence within 3 years (within 1 year for FCH) [27]

Typical recurrent HBV: 6-12 months post-transplant FCH: within 1 month posttransplant

Recurrent AIH Up to 40% [38] Variable Slow progression of

1-12 months post-transplant

6-12 or more months posttransplant

**Table 2.** Differential diagnosis of late post-transplant liver enzyme abnormalities

Rising alkaline phosphatase/GGT, late elevation in bilirubin

Elevated transaminases in typical recurrent HCV FCH: jaundice, marked elevation of alkaline phosphatase/GGT, extremely high HCV viral load

Elevated transaminases, elevated HBV viral load

transaminase elevation

CMV hepatitis: Elevated transaminases Extrahepatic CMV: gastroenteritis, colitis, pneumonitis

EBV hepatitis: usually asymptomatic PTLD: lymphoma-like presentation

**Clinical presentation Risk Factors Histological**

Inadequate immunosuppression, history of multiple episodes of or ongoing acute cellular rejection [17]

> FCH: excessive immunosuppression

Inadequate immunosuppression, native type II AIH

Graft from CMV-antibodypositive donor into CMVantibody-negative recipient

Primary infection: EBVantibody-negative recipient Progression to PTLD: excessive immunosuppression, preceding CMV infection [43]

**Characteristics**

195

Liver Biopsy After Liver Transplantation http://dx.doi.org/10.5772/52617

> Bile duct atrophy/loss, foamy arteriopathy [26]

Portal inflammation, interface hepatitis, lobular activity [28-30] FCH: cholestasis, fibrosis [35]

inflammation, Kupffer cell hypertrophy, lobular disarray; ground-glass hepatocytes; positive immunostaining for hepatitis B surface antigen and core antigen [37]

Lymphoplasmacytic portal infiltrate, prominent interface activity [29]

Portal inflammation, hepatocytes with CMV inclusions, focal bile duct damage [29]

EBV hepatitis: portal and sinusoidal infiltrates with atypical lymphocytes, +EBER PTLD: immunoblasts, with varying degrees of architectural distortion [45]

Inadequate prophylaxis Lymphoplasmacytic portal

**Figure 1.** Acute rejection, with endotheliitis (arrowhead), bile duct destruction (arrow), and mixed portal inflamma‐ tion (40x, H&E)


**Figure 1.** Acute rejection, with endotheliitis (arrowhead), bile duct destruction (arrow), and mixed portal inflamma‐

tion (40x, H&E)

194 Liver Biopsy - Indications, Procedures, Results

#### **5.7. Chronic rejection**

Chronic rejection involves immune-mediated injury to the hepatic arterial endothelium and bile duct epithelium. It is most commonly seen in patients who have experienced repeated bouts of significant ACR and/or have a recent history of inadequate immunosuppression. The typical clinical presentation is a slow rise in alkaline phosphatase/GGT, often followed by a rise in bilirubin. Procurement of an adequate biopsy sample (with at least ten complete portal triads) is crucial in the histologic diagnosis of chronic rejection [26]. The minimal cri‐ teria for diagnosis of chronic rejection, as defined by the 2000 Banff recommendations, are (1) bile duct atrophy/pyknosis affecting a majority of bile ducts (with or without bile duct loss); (2) foam cell obliterative arteriopathy (Figure 2); or (3) bile duct loss in greater than half of the portal tracts [26].

**5.8. Recurrent hepatitis C**

inent component of cholestasis and fibrosis [35].

Recurrent hepatitis C (HCV) infection is a universal phenomenon after liver transplantation, and exhibits an accelerated progression to advanced liver disease [27]. Particularly in the early months after transplant, the differential diagnosis of abnormal liver enzymes in HCV patients includes both ACR and recurrent HCV. These entities are usually distinguished his‐ tologically. Histologically established recurrent HCV demonstrates portal inflammation, of‐ ten with lymphoid aggregates, interface hepatitis, and lobular disarray [28-30] (Figure 3). There is often a component of ductular reaction, which is uncommon in HCV in native liv‐ ers [30]. While endotheliitis was traditionally considered specific to rejection, recent data demonstrate portal branch endothelitis in biopsies of native HCV livers [31,32]. It does ap‐ pear that moderate to severe central vein branch endotheliitis remains fairly specific for re‐ jection. In a prospective analysis of biopsies from 48 HCV transplant patients, Demetris et al described strict criteria to avoid overdiagnosis of ACR: (1) inflammatory bile duct injury in at least 50% of portal tracts, and/or (2) mononuclear perivenular inflammation with hepato‐ cyte necrosis in at least 50% of terminal hepatic venules [33]. In cases where the differentia‐ tion of ACR and recurrent HCV is not clear, the use of an immune function assay can be a useful adjunct [34]. Occasionally, recurrent HCV presents aggressively, in an entity known as fibrosing cholestatic hepatitis (FCH). The risk of FCH increases with aggressive immuno‐ suppression, such as that used to treat ACR. Histologically, FCH is distinguished by a prom‐

Liver Biopsy After Liver Transplantation http://dx.doi.org/10.5772/52617 197

**Figure 3.** Recurrent HCV, with chronic portal inflammation (ellipse), and interface as well as lobular activity (H&E,10x)

**Figure 2.** Foamy arteriopathy in the setting of chronic rejection (H&E 10x)

In the months and early years following liver transplant, recurrence of the underlying dis‐ ease which led to transplant becomes a common problem. Disease recurrence can be viral (most commonly hepatitis B or C), immunological (such as autoimmune hepatitis, primary sclerosing cholangitis [PSC], or primary biliary cirrhosis [PBC]), metabolic (such as non-alco‐ holic fatty liver disease [NAFLD]), malignant (hepatocellular carcinoma or cholangiocarci‐ noma), or idiopathic. The diagnosis of recurrent PSC, PBC, NAFLD, and malignancy is relatively straightforward and is therefore not discussed further. However, the degree of clinical and histological overlap between entities such as rejection, recurrent viral hepatitis, and autoimmune hepatitis can create diagnostic conundrums without close clinicopatholog‐ ical correlation.

#### **5.8. Recurrent hepatitis C**

**5.7. Chronic rejection**

196 Liver Biopsy - Indications, Procedures, Results

half of the portal tracts [26].

ical correlation.

**Figure 2.** Foamy arteriopathy in the setting of chronic rejection (H&E 10x)

In the months and early years following liver transplant, recurrence of the underlying dis‐ ease which led to transplant becomes a common problem. Disease recurrence can be viral (most commonly hepatitis B or C), immunological (such as autoimmune hepatitis, primary sclerosing cholangitis [PSC], or primary biliary cirrhosis [PBC]), metabolic (such as non-alco‐ holic fatty liver disease [NAFLD]), malignant (hepatocellular carcinoma or cholangiocarci‐ noma), or idiopathic. The diagnosis of recurrent PSC, PBC, NAFLD, and malignancy is relatively straightforward and is therefore not discussed further. However, the degree of clinical and histological overlap between entities such as rejection, recurrent viral hepatitis, and autoimmune hepatitis can create diagnostic conundrums without close clinicopatholog‐

Chronic rejection involves immune-mediated injury to the hepatic arterial endothelium and bile duct epithelium. It is most commonly seen in patients who have experienced repeated bouts of significant ACR and/or have a recent history of inadequate immunosuppression. The typical clinical presentation is a slow rise in alkaline phosphatase/GGT, often followed by a rise in bilirubin. Procurement of an adequate biopsy sample (with at least ten complete portal triads) is crucial in the histologic diagnosis of chronic rejection [26]. The minimal cri‐ teria for diagnosis of chronic rejection, as defined by the 2000 Banff recommendations, are (1) bile duct atrophy/pyknosis affecting a majority of bile ducts (with or without bile duct loss); (2) foam cell obliterative arteriopathy (Figure 2); or (3) bile duct loss in greater than

Recurrent hepatitis C (HCV) infection is a universal phenomenon after liver transplantation, and exhibits an accelerated progression to advanced liver disease [27]. Particularly in the early months after transplant, the differential diagnosis of abnormal liver enzymes in HCV patients includes both ACR and recurrent HCV. These entities are usually distinguished his‐ tologically. Histologically established recurrent HCV demonstrates portal inflammation, of‐ ten with lymphoid aggregates, interface hepatitis, and lobular disarray [28-30] (Figure 3). There is often a component of ductular reaction, which is uncommon in HCV in native liv‐ ers [30]. While endotheliitis was traditionally considered specific to rejection, recent data demonstrate portal branch endothelitis in biopsies of native HCV livers [31,32]. It does ap‐ pear that moderate to severe central vein branch endotheliitis remains fairly specific for re‐ jection. In a prospective analysis of biopsies from 48 HCV transplant patients, Demetris et al described strict criteria to avoid overdiagnosis of ACR: (1) inflammatory bile duct injury in at least 50% of portal tracts, and/or (2) mononuclear perivenular inflammation with hepato‐ cyte necrosis in at least 50% of terminal hepatic venules [33]. In cases where the differentia‐ tion of ACR and recurrent HCV is not clear, the use of an immune function assay can be a useful adjunct [34]. Occasionally, recurrent HCV presents aggressively, in an entity known as fibrosing cholestatic hepatitis (FCH). The risk of FCH increases with aggressive immuno‐ suppression, such as that used to treat ACR. Histologically, FCH is distinguished by a prom‐ inent component of cholestasis and fibrosis [35].

**Figure 3.** Recurrent HCV, with chronic portal inflammation (ellipse), and interface as well as lobular activity (H&E,10x)

#### **5.9. Recurrent hepatitis B**

Recurrent hepatitis B (HBV) infection was common in the era before combination prophy‐ laxis with hepatitis B immunoglobulin and oral antiviral agents. The current rate of recur‐ rent HBV (less than 10%) is attributed to a lack of prophylaxis for various reasons [36]. Histologically, recurrent HBV demonstrates lymphoplasmacytic portal inflammation, Kupffer cell hypertrophy, and lobular disarray [37]. Ground glass cells containing HBV sur‐ face antigen are often seen. Immunostaining demonstrates HBV surface antigen in hepato‐ cyte cytoplasm and HBV core antigen in hepatocyte nuclei. Recurrent HBV can also cause FCH, characterized by cholestasis, perisinusoidal fibrosis, and swollen hepatocytes with im‐ munoreactivity for HBV core antigen [37]. In patients without demonstrable HBV core anti‐ gen staining, other causes of hepatic dysfunction should be sought.

Liver transplant patients are also at risk of de novo infections due to their immunosup‐ pressed state. While the diagnosis of most of these infections is fairly straightforward, posttransplant cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infection can be more

Liver Biopsy After Liver Transplantation http://dx.doi.org/10.5772/52617 199

CMV is the most common clinically significant viral infection after solid organ transplanta‐ tion, with an incidence of up to 30% prior to the use of routine prophylaxis [41]. The risk of post-transplant CMV infection is greatest in CMV-antibody-negative recipients who receive a graft from a CMV-antibody-positive donor. Clinically, CMV infection can present with fe‐ ver, myelosuppression, and/or organ involvement (such as gastritis, colitis, hepatitis, or pneumonitis). While detection of CMV in the serum can provide a rapid diagnosis, a liver biopsy is often required to distinguish CMV from allograft rejection or demonstrate that both entities are present [42]. Typically, CMV hepatitis is characterized by mononuclear or mixed portal inflammation, focal bile duct damage, and hepatocytes with CMV inclusions (large eosinophilic nuclear inclusions surrounded by a clear halo [29] (Figure 5). Although some features similar to allograft rejection (portal lymphocytic inflammation, mild endothe‐ liitis) can be seen in CMV hepatitis, immunostaining for CMV antigens and/or the presence of CMV inclusions confirms that CMV is the driving force behind the hepatic dysfunction.

**Figure 5.** Hepatocyte with intranuclear CMV inclusion (arrowhead) (H&E, 100x)

difficult.

**5.11. CMV infection**

#### **5.10. Recurrent and** *de novo* **autoimmune hepatitis**

Recurrence of autoimmune hepatitis (AIH) can occur in up to 40% of patients, but the course is typically slowly progressive [38]. The biochemical/serological diagnosis of AIH [39] can be difficult in post-transplant patients, and therefore a liver biopsy is often required for a defin‐ itive diagnosis. In the chronic phase, recurrent AIH demonstrates lymphoplasmacytic portal infiltrate with prominent interface activity, perivenular activity and variable degrees of lob‐ ular necroinflammatory activity [29] (Figure 4). In patients without a pre-transplant history of AIH, the findings of lymphoplasmacytic infiltrate and perivenular activity, the differen‐ tial diagnosis includes recurrent HCV, rejection, and de novo AIH. This distinction relies on close clinicopathological correlation which takes into account the timing of onset, the immu‐ nosuppressive state, and the degree of perivenular damage [40].

**Figure 4.** Portal area with interface hepatitis, numerous plasma cells (arrowhead) and scattered eosinophils (arrow) (H&E, 40x)

Liver transplant patients are also at risk of de novo infections due to their immunosup‐ pressed state. While the diagnosis of most of these infections is fairly straightforward, posttransplant cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infection can be more difficult.

#### **5.11. CMV infection**

**5.9. Recurrent hepatitis B**

198 Liver Biopsy - Indications, Procedures, Results

(H&E, 40x)

Recurrent hepatitis B (HBV) infection was common in the era before combination prophy‐ laxis with hepatitis B immunoglobulin and oral antiviral agents. The current rate of recur‐ rent HBV (less than 10%) is attributed to a lack of prophylaxis for various reasons [36]. Histologically, recurrent HBV demonstrates lymphoplasmacytic portal inflammation, Kupffer cell hypertrophy, and lobular disarray [37]. Ground glass cells containing HBV sur‐ face antigen are often seen. Immunostaining demonstrates HBV surface antigen in hepato‐ cyte cytoplasm and HBV core antigen in hepatocyte nuclei. Recurrent HBV can also cause FCH, characterized by cholestasis, perisinusoidal fibrosis, and swollen hepatocytes with im‐ munoreactivity for HBV core antigen [37]. In patients without demonstrable HBV core anti‐

Recurrence of autoimmune hepatitis (AIH) can occur in up to 40% of patients, but the course is typically slowly progressive [38]. The biochemical/serological diagnosis of AIH [39] can be difficult in post-transplant patients, and therefore a liver biopsy is often required for a defin‐ itive diagnosis. In the chronic phase, recurrent AIH demonstrates lymphoplasmacytic portal infiltrate with prominent interface activity, perivenular activity and variable degrees of lob‐ ular necroinflammatory activity [29] (Figure 4). In patients without a pre-transplant history of AIH, the findings of lymphoplasmacytic infiltrate and perivenular activity, the differen‐ tial diagnosis includes recurrent HCV, rejection, and de novo AIH. This distinction relies on close clinicopathological correlation which takes into account the timing of onset, the immu‐

**Figure 4.** Portal area with interface hepatitis, numerous plasma cells (arrowhead) and scattered eosinophils (arrow)

gen staining, other causes of hepatic dysfunction should be sought.

nosuppressive state, and the degree of perivenular damage [40].

**5.10. Recurrent and** *de novo* **autoimmune hepatitis**

CMV is the most common clinically significant viral infection after solid organ transplanta‐ tion, with an incidence of up to 30% prior to the use of routine prophylaxis [41]. The risk of post-transplant CMV infection is greatest in CMV-antibody-negative recipients who receive a graft from a CMV-antibody-positive donor. Clinically, CMV infection can present with fe‐ ver, myelosuppression, and/or organ involvement (such as gastritis, colitis, hepatitis, or pneumonitis). While detection of CMV in the serum can provide a rapid diagnosis, a liver biopsy is often required to distinguish CMV from allograft rejection or demonstrate that both entities are present [42]. Typically, CMV hepatitis is characterized by mononuclear or mixed portal inflammation, focal bile duct damage, and hepatocytes with CMV inclusions (large eosinophilic nuclear inclusions surrounded by a clear halo [29] (Figure 5). Although some features similar to allograft rejection (portal lymphocytic inflammation, mild endothe‐ liitis) can be seen in CMV hepatitis, immunostaining for CMV antigens and/or the presence of CMV inclusions confirms that CMV is the driving force behind the hepatic dysfunction.

**Figure 5.** Hepatocyte with intranuclear CMV inclusion (arrowhead) (H&E, 100x)

#### **5.12. EBV infection and post-transplant lymphoproliferative disorder**

The clinical presentation of EBV infection can vary from asymptomatic hepatitis to posttransplant lymphoproliferative disorder (PTLD). Patients without pre-transplant immunity to EBV are at the greatest risk of infection. Patients with primary post-transplant EBV infec‐ tion, those with previous symptomatic CMV infection, and those with recent excessive im‐ munosuppression are at the highest risk for progression to PTLD [43]. EBV hepatitis typically demonstrates portal and sinusoidal infiltrates consisting of atypical lymphocytes. Often the lymphocytes are arranged in a single-file pattern within sinusoids [29]. Another histological pattern which can be seen in EBV hepatitis consists of mixed periportal and si‐ nusoidal infiltrates with large atypical mononuclear cells and immunoblasts, mild bile duct damage, and hepatic lobular activity [44]. The finding of EBV-encoded RNAs (EBERs) is confirmatory in most cases.

sies for HCV patients, and only 25% of centers perform protocol biopsies for other post-

Liver Biopsy After Liver Transplantation http://dx.doi.org/10.5772/52617 201

The rationale for protocol biopsies is the detection of those patients with severe dysfunction in the hopes that early treatment and/or change in immunosuppression might improve graft survival. However, the evidence of the clinical utility of these biopsies is conflicted. In stud‐ ies of long-term protocol biopsies in non-viral hepatitis transplant patients, it does appear that histological abnormalities in the setting of normal liver enzymes likely are not clinically significant [49,50]. The rationale for the use of protocol liver biopsies in HCV patients is the identification of those with severe HCV recurrence in the hopes that prompt treatment could improve graft survival [51]. This appears to be justified, as several studies have dem‐ onstrated the clinical utility of protocol biopsies in HCV patients, even as long as 20 years post-transplant [52-54]. It is notable, however, that the vast majority of patients with recur‐ rent HCV (and all patients with severe recurrent HCV) had abnormal liver enzymes at the

A separate but equally important factor in long-term patient survival is the avoidance of ex‐ trahepatic complications of chronic immunosuppression, including renal insufficiency, the development of diabetes mellitus, and infectious complications. In this regard, another utili‐ ty of protocol liver biopsy is the identification of those patients in whom immunosuppres‐ sion can be safely lowered. A retrospective study of patients with various liver diseases found that protocol biopsy results led to a change in immunosuppression in almost on third of patients [55]. Recently, an international working group developed recommendations for protocol biopsy monitoring in patients in whom minimizing or weaning immunosuppres‐

The liver allograft is susceptible to a broad range of insult and injury from the time that it is removed from the donor. While some complications are easily diagnosed by the clinical pre‐ sentation and advanced imaging, the majority of conditions display overlapping clinical fea‐ tures. As the treatment of these various conditions can be radically different, a definitive diagnosis is crucial. To that end, post-transplant liver biopsy continues to play a key role in the evaluation of liver transplant patients with hepatic dysfunction. While the role of proto‐ col biopsies in patients with no biochemical evidence of hepatic dysfunction has begun to fall out of favor (especially in non-HCV patients), the use of biopsy in immunosuppressionweaning protocols could promote a renewed interest in this methodology. The current data support the use of protocol biopsies in HCV patients (particularly in the first few years posttransplant). Areas for future investigation include non-invasive alternatives to liver biopsy such as immune assays and advanced imaging, and the use of routine protocol biopsies in

transplant patients [13].

pre-determined time of protocol biopsy.

sion is being considered [56].

weaning of immunosuppression.

**7. Summary**

PTLD is a heterogeneous lymphoproliferative disease divided into three main categories: early lesions, polymorphic PTLD, and monomorphic PTLD [45]. Early lesions demonstrate plasmacytic hyperplasia, and may or may not have prominent immunoblasts [29,45]. Poly‐ morphic PTLD is characterized by mixed infiltrates of monoclonal or polyclonal plasma cells, immunoblasts, and destruction of the underlying lymphoid architecture [45]. In monomorphic PTLD, most cases arise from B cell populations which demonstrate inva‐ sion, architectural effacement, and cellular atypia [29]. A fourth category, Hodgkin's lym‐ phoma-like PTLD, is sometimes described [46], and appears histologically like Hodgkin's lymphoma which occurs in non-transplant patients. PTLD patients with positive EBER re‐ sults may represent relatively better histopathological features than patients with EBERnegative PTLD [47].

### **6. Indication and protocol liver biopsies**

The majority of post-transplant liver biopsies are performed in response to changes in liver enzyme levels and/or abnormal imaging findings. Particularly in the early post-transplant period, these so-called "indication" biopsies are usually diagnostic and often result in a change in management. However, as patient and graft survival continues to improve, it has become clear that normal histology is rarely seen in the long-term liver graft [48]. What is not clear, however, is whether the histologic abnormalities seen in most late allograft biop‐ sies correlate to clinically-significant disease, and whether the routine use of so-called "pro‐ tocol" liver biopsies (performed at regular time points despite normal liver enzyme levels) is clinically justified. In our institution, we no longer perform annual protocol biopsies on pa‐ tients with alcoholic liver disease, non-alcoholic fatty liver disease, or cryptogenic liver dis‐ ease. The use of annual or semi-annual protocol biopsies in patients with AIH, PSC, or PBC is left to the discretion of the treating provider and/or the desires of the patient. In all HCV patients, protocol biopsies are performed at four months post-transplant, at one year posttransplant, and annually thereafter for at least the first five years. In contrast, an informal survey of 35 transplant centers found that only 65% of centers perform protocol liver biop‐ sies for HCV patients, and only 25% of centers perform protocol biopsies for other posttransplant patients [13].

The rationale for protocol biopsies is the detection of those patients with severe dysfunction in the hopes that early treatment and/or change in immunosuppression might improve graft survival. However, the evidence of the clinical utility of these biopsies is conflicted. In stud‐ ies of long-term protocol biopsies in non-viral hepatitis transplant patients, it does appear that histological abnormalities in the setting of normal liver enzymes likely are not clinically significant [49,50]. The rationale for the use of protocol liver biopsies in HCV patients is the identification of those with severe HCV recurrence in the hopes that prompt treatment could improve graft survival [51]. This appears to be justified, as several studies have dem‐ onstrated the clinical utility of protocol biopsies in HCV patients, even as long as 20 years post-transplant [52-54]. It is notable, however, that the vast majority of patients with recur‐ rent HCV (and all patients with severe recurrent HCV) had abnormal liver enzymes at the pre-determined time of protocol biopsy.

A separate but equally important factor in long-term patient survival is the avoidance of ex‐ trahepatic complications of chronic immunosuppression, including renal insufficiency, the development of diabetes mellitus, and infectious complications. In this regard, another utili‐ ty of protocol liver biopsy is the identification of those patients in whom immunosuppres‐ sion can be safely lowered. A retrospective study of patients with various liver diseases found that protocol biopsy results led to a change in immunosuppression in almost on third of patients [55]. Recently, an international working group developed recommendations for protocol biopsy monitoring in patients in whom minimizing or weaning immunosuppres‐ sion is being considered [56].

### **7. Summary**

**5.12. EBV infection and post-transplant lymphoproliferative disorder**

confirmatory in most cases.

200 Liver Biopsy - Indications, Procedures, Results

negative PTLD [47].

**6. Indication and protocol liver biopsies**

The clinical presentation of EBV infection can vary from asymptomatic hepatitis to posttransplant lymphoproliferative disorder (PTLD). Patients without pre-transplant immunity to EBV are at the greatest risk of infection. Patients with primary post-transplant EBV infec‐ tion, those with previous symptomatic CMV infection, and those with recent excessive im‐ munosuppression are at the highest risk for progression to PTLD [43]. EBV hepatitis typically demonstrates portal and sinusoidal infiltrates consisting of atypical lymphocytes. Often the lymphocytes are arranged in a single-file pattern within sinusoids [29]. Another histological pattern which can be seen in EBV hepatitis consists of mixed periportal and si‐ nusoidal infiltrates with large atypical mononuclear cells and immunoblasts, mild bile duct damage, and hepatic lobular activity [44]. The finding of EBV-encoded RNAs (EBERs) is

PTLD is a heterogeneous lymphoproliferative disease divided into three main categories: early lesions, polymorphic PTLD, and monomorphic PTLD [45]. Early lesions demonstrate plasmacytic hyperplasia, and may or may not have prominent immunoblasts [29,45]. Poly‐ morphic PTLD is characterized by mixed infiltrates of monoclonal or polyclonal plasma cells, immunoblasts, and destruction of the underlying lymphoid architecture [45]. In monomorphic PTLD, most cases arise from B cell populations which demonstrate inva‐ sion, architectural effacement, and cellular atypia [29]. A fourth category, Hodgkin's lym‐ phoma-like PTLD, is sometimes described [46], and appears histologically like Hodgkin's lymphoma which occurs in non-transplant patients. PTLD patients with positive EBER re‐ sults may represent relatively better histopathological features than patients with EBER-

The majority of post-transplant liver biopsies are performed in response to changes in liver enzyme levels and/or abnormal imaging findings. Particularly in the early post-transplant period, these so-called "indication" biopsies are usually diagnostic and often result in a change in management. However, as patient and graft survival continues to improve, it has become clear that normal histology is rarely seen in the long-term liver graft [48]. What is not clear, however, is whether the histologic abnormalities seen in most late allograft biop‐ sies correlate to clinically-significant disease, and whether the routine use of so-called "pro‐ tocol" liver biopsies (performed at regular time points despite normal liver enzyme levels) is clinically justified. In our institution, we no longer perform annual protocol biopsies on pa‐ tients with alcoholic liver disease, non-alcoholic fatty liver disease, or cryptogenic liver dis‐ ease. The use of annual or semi-annual protocol biopsies in patients with AIH, PSC, or PBC is left to the discretion of the treating provider and/or the desires of the patient. In all HCV patients, protocol biopsies are performed at four months post-transplant, at one year posttransplant, and annually thereafter for at least the first five years. In contrast, an informal survey of 35 transplant centers found that only 65% of centers perform protocol liver biop‐

The liver allograft is susceptible to a broad range of insult and injury from the time that it is removed from the donor. While some complications are easily diagnosed by the clinical pre‐ sentation and advanced imaging, the majority of conditions display overlapping clinical fea‐ tures. As the treatment of these various conditions can be radically different, a definitive diagnosis is crucial. To that end, post-transplant liver biopsy continues to play a key role in the evaluation of liver transplant patients with hepatic dysfunction. While the role of proto‐ col biopsies in patients with no biochemical evidence of hepatic dysfunction has begun to fall out of favor (especially in non-HCV patients), the use of biopsy in immunosuppressionweaning protocols could promote a renewed interest in this methodology. The current data support the use of protocol biopsies in HCV patients (particularly in the first few years posttransplant). Areas for future investigation include non-invasive alternatives to liver biopsy such as immune assays and advanced imaging, and the use of routine protocol biopsies in weaning of immunosuppression.
