**7. Conclusions**

male [14]. The clinical picture reflects the presence of mass lesion and is dominated by ab‐ dominal pain [113]. The other manifestations and complications include jaundice, cholangitis, tumour rupture [114], haemorrhage [115], compression of the portal or caval veins with possible subsequent ascites [113], hemobilia [12] and mucobilia [116]. Notably, the tumour can progress slowly [117] with the clinical history of biliary cystadenocarcinoma as long as 10-15 years [112,118]. The long course is is in accordance with the low grade of malignancy and gradual development of tumour through stages of increased epithelial pro‐ liferation, dysplasia, *in situ* cancer and, finally, invasive cancer. Thus, long anamnesis of cystic hepatic mass does not exclude the possibility of malignant tumour and the need for careful follow-up if the cyst is not removed by operation. Although biopsy can be consid‐ ered in cases with unclear differential diagnosis, it is not the first choice because of the fol‐ lowing considerations. First, simple liver cyst is the main differential diagnosis of cystic biliary tumours. Although biliary cystadenocarcinoma is rare, liver cysts have high preva‐ lence being present in 2.5% of the population [119] and cannot be distinguished from cystic biliary tumours on the basis of CA19-9 and CEA levels [14,114]. However, core biopsy is un‐ likely to yield sufficient tissue in case of simple cyst or cystadenoma; it also is not suitable for the diagnostics of focal malignancy and rarely can lead to peritoneal carcinomatosis [13]. Therefore radiological diagnostics, especially computed tomography, is essential [117]. Grossly, biliary cystadenocarcinoma is multicystic. Internal mural nodules are irregularly distributed in the walls. The tumour most frequently is located within the liver (83%). Extrahepatic bile ducts (13%) or the gall bladder (0.02%) has been affected by this tumour as well [14]. The size of cystic biliary tumours (1.5-30 cm) is not helpful in the differential diagnos‐ tics between simple hepatic cyst and cystic biliary tumours; it also has no correlation with malignant biological potential [120]. The metastatic spread of biliary cystadenocarcinoma can affect the liver, regional lymph nodes in the hepatoduodenal ligament, lungs, pleura or peritoneum [100]. Histologically, biliary cystadenocarcinoma is characterised by clear-cut signs of malignancy: cellular atypia, particularly nuclear polymorphism, mitotic activity and invasion into surrounding stroma. The tumour architecture is cystic and papillary. The be‐ nign counterpart of biliary cystadenocarcinoma, the biliary cystadenoma lacks the malig‐ nant features [100] and is composed by either mucinous or serous benign epithelium. Most of cystic biliary tumours possess characteristic mesenchymal, ovarian–type stroma. Hypo‐ thetically, these tumours arise from bile ducts proximal to the hilum of the liver and share the cystic structure and presence of peculiar ovarian-type mesenchymal stroma with muci‐ nous cystic tumours of the pancreas and retroperitoneum, leading to the hypothesis that ec‐ topic ovarian stroma during embryogenesis can become incorporated along the biliary tree, in the pancreas and retroperitoneal space and cause the proliferation of the adjacent epitheli‐ um by production of the hormones and growth factors [121]. Origin from intrahepatic peri‐ biliary glands [122] or from ectopic rests of primitive foregut sequestered in the liver [114] has been hypothesised. Development from pluripotential stem cells is suggested on the ba‐ sis of the presence of albumin messenger RNA and biliary type cytokeratins in the tumour cells [123]. Biliary cystadenocarcinoma without mesenchymal stroma more frequently arises in males and carries poorer prognosis in comparison with the tumour possessing mesenchy‐ mal stroma [122]. By immunohistochemistry, increasing proliferative activity by Ki-67 ex‐

146 Liver Biopsy - Indications, Procedures, Results

In conclusion, wide variety of neoplastic processes can affect the liver. Most of non-cystic tumours can be reliably diagnosed in liver biopsy. Several demographic and clinical data should be submitted along with the liver biopsy. Patient's age and presence or absence of clinical symptoms must be known. If there is history of contraceptive use it should be report‐ ed. Radiological data have high relevance: the size, localisation in respect to liver capsule and number of focal liver lesions should be known to the pathologist. The vascularity should be described. Knowing these data, pathologist should evaluate the haematoxylin-eosin stained specimen. Wide panel of immunohistochemical stains can be recommended than.
