Pathologist's perspective on liver needle biopsy size?

Liver needle biopsies can generally be divided into two diameter categories: (1) large needle biopsies (LNB) with a minimum core diameter of 1.0 mm (e.g. Menghini), which are recommended for the investigation of diffuse diseases [1–3]; and thin needle biopsies (TNB) with an internal diameter of less than 1.0 mm, which are more often employed for the investigation of focal lesions [2–6]. The manuscript by Colloredo in this issue examines the question, ‘does the size of the liver needle biopsy significantly influence the histopathological grading and staging of chronic viral hepatitis?” This is an important question to answer because the grade, or current level of necro-inflammatory activity, and stage, or amount of fibrosis and architectural distortion, can influence patient management. The intuitive response to this manuscript by most pathologists, including those that specialize in liver biopsy interpretation, is likely to be positive because we all like to see more tissue and be more certain of our diagnoses. Pathologists however, have to be aware of clinical constraints. In general, the mortality rate and risk of serious complications is higher with patients with tumors [7], and in unguided LNB than with image-guided TNB [8,9]. In addition, Tru-cut or cutting biopsy devices are associated with a higher rate of bleeding compared to aspiration-type biopsy (e.g. Menghini) [7], but the latter types show an increased rate of fragmentation. However, the difference in complication rates between needle types can be decreased by using spring-loaded guns, which utilize a Tru-cut technology, but mechanically control the sequence of movements so the time of the intra-hepatic phase is minimized [7]. This decreases the risk of respiratory movements causing needle shear in the liver. In addition, blinded needle biopsies have a higher rate of complications compared to image-guided biopsies [7]. Biopsies of focal lesions can be made even more accurate and safe using direct laparoscopic guidance because the liver is visualized and the biopsy tract can be treated [7]. A transjugular approach can be used in patients with frank liver failure and significant coagulopathy. Clinical situations in which unguided LNB carries a high risk of complications or might even be contraindicated include an uncooperative patient, thrombocytopenia (platelet counts ,50,000 mm), prothrombin time 4 s above normal, bleeding time over 10 min, infection in needle path, severe anemia, significant ascites, suspected high-grade extra-hepatic biliary obstruction, cholangitis, echinococcal cyst, anastomotic abnormalities, significant ascites, and Child-Pugh stages B and C [3,7]. The increased risk of bleeding in tumor patients is probably related to increased tumor vascularity. The study by Colloredo attempts to establish the point that utilization of TNB could result in a directional bias toward ‘under calling’ the grade and stage of chronic hepatitis when using the Ishak system [10]. They did this by reading a series of LNB, which were at least 3 cm long and 1.4 mm wide. Subsequently, these same biopsies were re-read after being made shorter and/or thinner by covering the slide with opaque paper to decrease the length or viewing the slide through a modified micrometer eyepiece to decrease the width. Therefore, the authors recommend avoiding the use of TNB, if possible, when the purpose of the biopsy is to grade or stage chronic hepatitis. The authors attributed the bias seen in TNB to less tissue and consequently, a smaller number of portal tracts. The smallest number of portal tract had greatest impact on scoring for portal inflammation and fibrosis, presumably because the most inflamed or fibrotic portal tracts had been excluded from the sample. One might expect that a reduction in size would increase the number of inadequate specimens, and decrease the reliability and accuracy, but not necessarily lead to trend toward less severe disease. In my opinion, the study of Colloredo et al. raises valid