Leberparenchymknoten bei pathologischer hepatischer Vaskularisation/Perfusion

Senescence markers in focal nodular hyperplasia of the liver: pathogenic considerations on the basis of immunohistochemical results

Focal nodular hyperplasia (FNH) is a polyclonal tumour-like hepatic lesion characterised by parenchymal nodules, connective tissue septa without interlobular bile ducts, pronounced ductular reaction and inflammation. It may represent a response to local arterial hyperperfusion and hyperoxygenation resulting in oxidative stress. We aimed at obtaining closer insight into the pathogenesis of FNH with its characteristic morphologic features. Immunohistochemistry and immunofluorescence microscopy was performed on FNH specimens using antibodies against keratins (K) 7 and 19, neural cell adhesion molecule (NCAM), lamin B1, senescence markers (CDK inhibitor 1/p21^Cip1, CDK inhibitor /p16^Ink4a, senescence-associated (SA) β- galactosidase activity), proliferation markers (Ki-67, proliferating-cell nuclear antigen (PCNA)), and the abnormally phosphorylated histone γ-H2AX, indicating DNA double strand breaks; moreover SA β- galactosidase activity was determined histochemically. Ductular metaplasia of hepatocytes indicated by K7 expression in the absence of K19 plays a major role in the development of ductular reaction in FNH. Moreover, the expression of senescence markers (p21^Cip1, p16^Ink4a, γ-H2AX, SA β-galactosidase activity) in hepatocytes and cholangiocytes suggests that stress-induced cellular senescence contributes to fibrosis and inflammation via production of components of the senescence-associated secretory phenotype. Expression of proliferation markers (Ki-67, PCNA) was not enhanced in hepatocytes and biliary cells. Senescence and ductular metaplasia of hepatocytes may thus be involved in inflammation, fibrosis and apoptosis resistance. Hence, fibrosis, inflammation and reduced apoptotic cell death, rather than proliferation (hyperplasia) may be responsible for increased tissue mass and tumour-like appearance of FNH.

[Liver sinusoids: pathology of endothelial findings]

This review covers a spectrum of pathologic changes and diseases involving hepatic sinusoids. In the majority of patients, clinical findings are rather uncharacteristic such as hepatomegaly, portal hypertension, or lingering liver failure of unknown origin. In contrast to more common hepatic disorders, characteristic clinical, serological, immunoserological, and radiographical findings are lacking. In these cases, biopsy findings may be crucial to guide treatment decisions. This review covers a variety of hepatic disorders that practicing pathologists may encounter in their clinical routine.

Intrahepatic cholestasis in common chronic liver diseases

BACKGROUND AND OBJECTIVE

Cholestasis represents the consequence of impaired bile formation and decrease in bile flow, generally classified as extra- and intrahepatic. Cholestasis is the pivotal hallmark of the so-called primary cholestatic liver diseases but may also emerge in other forms of chronic liver injury. The aim now was to summarise the current state of knowledge on intrahepatic cholestasis related to chronic liver diseases.

METHODS

For this overview on intrahepatic cholestasis in chronic liver disorders other than the 'classic' cholestatic liver diseases, selected references were retrieved by literature search in MEDLINE and textbooks were reviewed. All articles were selected that discussed pathophysiological and clinical aspects of intrahepatic cholestasis in the context of alcoholic liver disease, nonalcoholic fatty liver disease, chronic hepatitis B and C virus infections as well as drug-induced and granulomatous liver diseases. Titles referring to primary biliary cirrhosis and sclerosing cholangitis were excluded.

RESULTS AND CONCLUSIONS

Dependent on the aetiology, intrahepatic cholestasis is present at variable frequencies and in different disease stages in chronic liver diseases. Cholestasis secondary to chronic liver injury may denote a severe disease course and development of end-stage liver disease or specific disease variants. These findings indicate that 'secondary intrahepatic cholestasis' (SIC) can occur in the natural course of chronic liver diseases other than the primary cholestatic diseases, in particular in the setting of advanced disease progression.

[Focal nodular hyperplasia in a 12-year-old boy: case report and considerations]

BACKGROUND

Focal nodular hyperplasia (FNH) is a benign hepatic tumor of unknown origin. It is only observed rarely in children (approximately 1-2% of all pediatric liver tumors).

CASE REPORT

A 12-year-old boy who suffered from infectious mononucleosis with liver involvement and hepatomegaly underwent a sonographic scan of the liver at an external hospital 3 months after the infection disappeared which revealed a tumor of the left hepatic lobule. Subsequent further examination (abdominal CT and MRT scans) confirmed the diagnosis of a highly vascularized mass about 10 cm in diameter, suspicious for FNH. Due to the high vascularization no biopsy was performed. A preoperative angiographic coiling and complete surgical resection was carried out because of the size and morphologic uncertainty. The diagnosis of FNH was confirmed by histological examination. The annual sonographic examination at follow-up has been uneventful for a 4-year period.

CONCLUSIONS

Due to the rarity the diagnosis of FNH in children can be difficult leading to differential diagnostic problems. Due to the risk of bleeding in larger size tumors a biopsy is a point of controversy. Complete resection and histopathological examination of FNHs in childhood is a mandatory therapeutic option, which may be indicated in large tumors or, as in the present case tumors of uncertain biological behaviour.

Hepatocellular carcinoma in biliary atresia: King's College Hospital experience

OBJECTIVES

To establish risks for development of hepatocellular carcinoma (HCC) in children with biliary atresia (BA), the most common chronic liver disease of childhood.

STUDY DESIGN

In our tertiary referral center database we have identified children with BA who had development of or have been incidentally found to have HCC. Their demographic, clinical, radiologic, and histologic features were analyzed.

RESULTS

Between 1990 and 2008, 387 infants were diagnosed with BA at our center. Of these, three (0.8 %) who underwent operation at a median age of 68 (range 66 to 71) days had development of a histologically proven HCC detected at a median age of 2.1 (range 1.8 to 4.9) years. Another two, referred later, were diagnosed with HCC on their liver explants at ages 1.1 and 17.75 years, respectively. Overall, two had elevated serum levels of alpha-fetoprotein. All five children underwent successful liver transplantation at a median age of 2.1 years (range 1.1 to 17.75) and remain well after a median of 2.5 (range 2 to 5.7) years.

CONCLUSION

HCC develops in a small percentage of children with BA. Serum alpha-fetoprotein levels and ultrasound screening are helpful but not absolute markers of the malignant change. In the absence of the extrahepatic involvement, liver transplantation represents an effective treatment.

Liver neoplasia in children

Management of pediatric liver tumors has significantly improved over the last 2 decades. The management options for hepatocelluar carcinoma (HCC) are not well defined. In the pediatric context, the main clinical aims are to reduce chemotherapy toxicity (predominantly ototoxicity and nephrotoxicity) in children treated for hepatoblastoma and to investigate additional modes of treatment for HCC. An increasing number of children develop HCC in the background of chronic liver disease, and screening methods need to be better observed.

Agrin and CD34 immunohistochemistry for the discrimination of benign versus malignant hepatocellular lesions

Agrin is a recently identified proteoglycan component of vascular and bile duct basement membranes in the liver. The selective deposition of agrin in hepatocellular carcinoma (HCC) microvessels versus sinusoidal walls prompted us to investigate the utility of agrin immunohistochemistry (IHC) in detecting malignant hepatocellular lesions. We focused on the differential diagnostic problems often presented by hepatocellular adenomas (HCAs) and dysplastic nodules. IHC for agrin was performed on 138 formalin-fixed, paraffin-embedded surgical specimens from 93 patients, including cirrhotic liver tissues (25), focal nodular hyperplasia (10), large regenerative nodules (8), low-grade (23) and high-grade (7) dysplastic nodules, small HCC (8), HCC (27), and HCA (30). Agrin immunostaining was compared with that of CD34 and, in selected cases, to glypican-3. The combination of agrin and CD34 sensitively (0.94) and specifically (0.93) identified lesions judged previously as malignant by histology. The majority of benign lesions were clearly agrin-negative, whereas the strength and extent of agrin IHC faithfully reflected dysplasia in "atypical" HCAs and in high-grade dysplastic nodules. Malignant lesions were uniformly positive. In conclusion, as agrin is highly selective for tumor blood vessels, IHC for agrin facilitates the discrimination of benign and malignant hepatocellular lesions. Moreover, whereas glypican-3 in some HCCs may appear in few scattered cells only, agrin is diffusely deposited in virtually all malignant lesions, which may prove advantageous in the evaluation of small specimens such as core biopsies.

[Diagnosis and differential diagnosis of benign liver tumors and tumor-like lesions]

Benign liver tumors and tumor-like lesions cover a broad spectrum of differential diagnoses, varying from dysontogenetic cysts to pseudolesions. Focal nodular hyperplasia, adenoma and regenerating nodules play a major role in clinical practice. Based on imaging findings, these lesions can be classified as cystic or solid, solitary or multiple, and hyper- or hypovascular. Haemangioma, FNH, steroid-associated adenoma, cystadenoma and echinococcus cysts can be reliably diagnosed using imaging techniques. The same is true for pseudolesions, which are found in particular on dynamic computed tomography. Other entities such as adenoma in cirrhotic livers, angiomyolipoma, regenerating nodules or Echinococcus alveolaris cannot be safely diagnosed by imaging and require biopsy. Morphological and functional characteristics of the most common lesions in the different imaging modalities will be discussed. Where possible, a diagnostic strategy will be presented.

[Pathology along the liver sinusoids: endothelial and perisinusoidal findings]

Sinusoidal alterations unrelated to primary hepatocellular damage present without characteristic clinical findings and in these cases the liver biopsy is particularly important. Capillarization of sinusoids is characterized by closing of fenestration, formation of a basal membrane and by the expression of CD34 and is typical for active cirrhosis. In nodular regeneratory hyperplasia, capillarization indicates a local or general disturbance of perfusion. In large regenerative nodules, focal nodular hyperplasia and liver cell adenoma CD34-positive capillaries reflect afferent parts and CD34-negative sinusoids the efferent parts of the parenchymal vascular bed. HCC generally have a completely capillarized CD34-positive vascular bed. Hepatic angiosarcomas and epithelioid hemangioendotheliomas can be easily overseen in liver biopsies, if they spread along the sinusoids without detoriation of the acinar architecture and without significant alteration of the surrounding liver cell plates. Toxic damage of endothelial cells, post-sinusoidal stasis and sinusoidal hyperperfusion are the underlying pathogenetic principles of sinusoidal injury. Rupture and loss of the perisinusoidal reticulin fibres lead to peliosis hepatis. In these cases liver biopsy might disclose occlusion of the terminal liver veins (VOD). Perisinusoidal fibrosis can be caused by intrasinusoidal accumulation of pathologic cells, advanced intrasinusoidal macrophagocytic storage diseases and by activation of the vitamin A-storing hepatic stellate cells. Perisinusoidal amyloidosis can be the first sign of an underlying B-cell neoplasia.