Cellular and Molecular Pathology - Case Study Example

Cellular and Molecular Pathology (Case Study Assignment) Tissue histopathological studies have become the gold standard for the diagnosis of a variety of liver diseases. According to the generally accepted criteria, following are the indications for liver biopsy: chronic hepatitis, Wilson`s disease, alcoholic hepatitis, non-alcoholic steatohepatitis, primary biliary cirrhosis, cholestatic liver disease, fever of unknown origin, liver mass, status of liver post-transplantation and of donor pre-transplantation (Bravo et al, 2001) Though it is generally accepted that liver biopsy specimen is no more than 1/150,000 part of the whole liver mass, but this is considered to be adequately representative of the diseased organ. Recently guidelines suggest an adequate biopsy specimen to be 20- 25 mm long and consisting of 11 complete portal tracts (Cholongitas et al, 2006); this might be less when it comes to focal lesions, such as in this particular patient. In the given case study, the MRI scan confirms the presence of solid mass lesion in the right middle lobe of liver. In this scenario the possible etiology of the lesion might be one of the following: Haemangioma, Adenoma, Liver abscess (amebic or pyogenic), Focal nodular hyperplasia, Fatty infiltration, Rare primary liver neoplasms, Hepatocellular cancer, Cholangiocarcinoma, and metastatic lesions. Various studies have focused on the quality of liver biopsy samples with regards to sampling errors, length of specimen, potential heterogeneity of diseased liver, needle size and the methods of biopsy (Cholongitas et al, 2006). In one review, sampling errors have been reported all over the world to be the limiting factor for an adequate liver biopsy specimen, further increasing the inter-observer and the intra-observer variation for the chronic liver disease biopsy evaluation (Cholangitas et al, 2006). However, newly devised scoring systems lessen these chances. Bedossa et al (2003) have concluded that increasing the size of biopsy and multiple specimens can lower the sampling variability and overcome effects of heterogeneity in diffuse liver disease. Another review reported that adequate sample should be ≥25 mm rather than ≥15 mm and the number of CPTs should be ≥11 rather than ≥6-8. This criterion is difficult to achieve but it has been shown to be associated with adequate information in the biopsy sample (Cholangitas et al, 2006). The same review stated that samples obtained with Mahingini needles were associated with longer samples, but the Tru cut needle`s large shaft must decrease the discrepancy, if any. Most of the above mentioned criteria for quality of liver biopsy sample are generally for the diffuse liver diseases, but in our case study the lesion is focal, thus the most optimum quality of sample will be the one that visualizes enough cellular architecture and their details to identify type of cell from which it is arising. Liver masses or focal lesions are especially difficult to evaluate on biopsy; this may be because of the cystic or vascular nature of the mass and therefore imaging remains an important pre-requisite for such focal lesions and ultrasound guidance must be also provided. Another important aspect is the presence of diseased background parenchyma e.g: cirrhosis, which necessitates taking another biopsy tissue from distant site as well as from the actual mass lesion (Rockey et al, 2009). The most widely used method of sampling is the Percutaneous Liver biopsy, which is undertaken only after comparing the risk factors with the disease morbidity. It can be further specified by ultrasound guided undertaking of the procedure and plugging the site of biopsy afterwards (Mayoral & Lewis, 2001). It takes only few seconds though number of passes increase complications after 2 attempts. The mortality of 0.01%- 0.1% and morbidity due to small complications of 5.9% has been reported in text books. It might be complicated by hemorrhage and pain. Percutaneous Liver Biopsy is absolutely contraindicated in uncooperative patient, bleeding tendency, unexplained bleeding, vascular tumor, inappropriate blood transfusion availability (Bravo et al, 2001). Severe coagulopathy and ascites calls for trans-jugular biopsy. Laparoscopic and Fine Needle Aspiration Biopsy are also attempted in certain cases. Routinely the liver biopsy specimen is immersed immediately in Formol saline or 10% neutral buffered formalin/ NBF, and kept floating in the fixative solution; bloating paper and sponge packing must be avoided. Tissue must be embedded flat to avoid discontinuity of histologic evidence. The sample can be kept within fine mesh cassettes or lens film wrapping. For focal mass lesions, generally 2 slides of H & E and trichrome stains are made first. NBF has well cross linking characteristics and it is an adequate fixative and the immunochemistry staining is exclusively done with formalin fixation since it is adequate for most antibody fixation. It is recommended to validate the timing for fixation for individual antibody (generally 6- 12 hour are enough) (Mortensen & Brown, 2003). Trichrome stain is used to assess fibrosis, which will give idea about presence of underlying parenchymal cirrhosis, to grade and stage the disease process, if any. Similarly Reticulin stain can point out the general architecture, necrotic and degenerating hepatocytes (Centeno, 2006). Mucaramine stain that detects mucin in the tumor cells can also be used in this case study to evaluate for the presence of adenocarcinoma. The immunochemical staining of liver biopsies is utilized for viral protiens, structural proteins and secretory materials. For instance, Cytokeratins K7 and K19 are present in biliary epithelium, K8 and K18 Hepatocyte-specific antigen (HepPar1) in hepatocytes, CD68 and HLA-DR in Kupffer cells, enzyme transporters such as Gamma-glutamyl-transpeptidase (GGT), Bile salt export protein (BSEP), and Multidrug resistance 3 (MDR3) (Portmann, 2012). Cirrhotic liver with tumor does not usually require immunohistochemistry because most common cancers are primary in origin; however immunohistochemistry assumes importance when we suspect metastatic neoplasms which are the most common neoplasms in the non-cirrhotic liver. Gastro intestinal tract and neuroendocrine tumors are the most common metastatic lesions observed in the liver biopsy specimen. Since in the current scenario, there is history of Colonic adenocarcinoma, we must promptly see the biopsy taken from the liver mass for Carcino embryonic antigen (CEA), CA 19.9, GGT and, PHI to find out if the mass has arisen from colon or not. The CEA is strongly positive in the cytoplasm of carcinomatous cells of colon carcinomas, some other tumors also stain mildly positive for it. Normal enterocytes display CEA exclusively at the luminal epithelium. The techniques applied for immunohistochemical staining either make use of indirect methods to labeled antibody or utilize enzyme visualization on the paraffin fixed tissues. For instance in this particular case: according to the IHC Protocols for staining CAE, a primary unlabeled antibody obtained from market consisting of rabbit anti human clone of CAE antibody is utilized to react with CEA present in the cytoplasm of colonic cancerous cells of the liver biopsy specimen. Non-specific binding and endogenous enzymes may be necessary to be blocked in some cases. The second reagent (anti IgG antibody) that will bind to the unlabeled antibody, (combined already with the target antigen) can either be an enzyme or fluorescent reporter. Horseraddish peroxidase (an enzyme reporter) is reacted with a substrate (such as Diaminobenzidine/ DAB) and when the reaction proceeds, a dark brown or purple staining is observed with white light if the enzyme is active. This is one of the methods by which we can confirm the presence of CEA positive colonic tumor cells in the liver biopsy specimen; this will signify that the suspicion of colonic cancer reoccurrence was true. On the other hand if the staining showed canallicular rather than cytoplasmic distribution, it will direct towards the hepatocellular origin of the mass (Khadim, et al, 2011). Monoclonal antibody such as Arcitomomab directed against CEA; and reconstituted along with radionuclide Technitium can also be used to detect body tissues with high expression of CAE. This relies on use of SPECT (single photon emission computed tomography) to take images displaying progression, remission or spread of the colorectal carcinoma. But also there are other techniques available to detect the origin of the mass lesion obtained from the liver biopsy specimen. Some of the molecules such as Hep Par- 1, CK 20, CK 7 and AFP immunohistochemistry can be utilized to differentiate metastatic from primary liver neoplasms. Liver is the second most common organ where secondary metastasis occurs, and it has been reported that hepatocellular carcinomas can mimic adenocarcinoma, renal cell carcinoma, adrenal cortical carcinomas and cholangiocarcinomas, which makes differentiation all more important (Khadim et al, 2011). As mentioned above a monoclonal antibody named CA 19.9 targeted against tumor cell structure has been reported to be positive in nearly 30% of the colonic carcinoma patients, as well in other gastrointestinal cancers, though it is not currently utilized unlike CEA for detecting reoccurrence and seeing prognosis of the tumor. Electron microscopy finds limited role in liver pathologies except in case of mitochodropathies and metabolic enzyme deficiency states. The newest techniques such as morphometery and multiphoton fluorescent microscopy have been developed during past 10 years to analyze the ultra-structural shape quantification. Thus, the most appropriate procedure after H & E, and mucaramine staining is immune histochemistry detection of CAE in the liver biopsy specimen using either chromogen or flourescent reporters. References Bedossa P, Dargère D, Paradis V. (2003) Sampling variability of liver fibrosis in chronic hepatitis C. Hepatology 2003; 38: 1449-1457. Bravo AA, Sheth SG, Chopra S. (2001) Liver Biopsy. N Eng J Med 2001; 344(7):495-500 Centeno, B. A. (2006). Pathology of Liver Metastasis.Cancer Control, 13(1), 12- 26 [Online] Available from http://www.ncbi.nlm.nih.gov/pubmed/16508622 [Accessed on 29th January 2013] Cholongitas, E., Senzolo, M., Standish, R., Marelli, L., Quaglia, A., Patch, D., ... & Burroughs, A. K. (2006). A systematic review of the quality of liver biopsy specimens. American journal of clinical pathology, 125(5), 710-721. IHC World (n.d.).Carcinoembryonic Antigen (CEA) Antibody Staining Protocol for Immunohistochemistry.[Online] Available from http://www.ihcworld.com/_protocols/antibody_protocols/cea_biocare_medical.htm [Accessed on 29th January 2013] Khadim, M. T., Jamal, S., Ali, Z., Akhtar, F., Atique, M., Sarfraz, T., & Ayaz, B. (2011). Diagnostic Challenges and Role of Immunohistochemistry in Metastatic Liver Disease. Asian Pacific Journal of Cancer Prevention, 12, 373-376. Mayoral, W., & Lewis, J. H. (2001). Percutaneous Liver Biopsy. Digestive diseases and sciences, 46(1), 118-127. Mortensen, E., & Brown, J. M. (2003). Effects of fixation on tissues. Methods in molecular medicine, 81, 163-180. Portmann, B. (2012). Liver Biopsy in the Assessment of Medical Liver Diseases. Royal College of Pathologists, London [Online] Available from http://www.virtualpathology.leeds.ac.uk/eqa/liverdocs/20120329/Bernard.pdf [Accessed on 29th January 2013 Rockey, D. C., Caldwell, S. H, Goodman, Z. D. et al. (2009) Liver Biopsy, Hepatology, 2009 1017-1044 Read More