Introduction

Liver biopsy is one of many diagnostic tools used in the evaluation and management of patients with liver disease. It continues to play an important role because the concepts and classifications of liver disease are rooted in morphology. Moreover, looking at a liver biopsy specimen through the microscope is a very direct way of visualising the morphological changes that affect the liver in disease. The pathologist’s interpretation (rather than mere enumeration) of these changes is used to answer important clinical questions such as disease causation and activity, and is important in therapeutic decision-making.¹ A thorough and informed interpretation of liver biopsy findings therefore stands to have substantial impact on patient care. It bears emphasising that the evidence base² for much of liver biopsy interpretation rests on the large body of important observations reported in the pathology literature during the past five decades, since Menghini in 1958 first introduced the technique of percutaneous needle biopsy.³ Questions of a more basic pathobiological nature can also be addressed by applying contemporary techniques of molecular and genomic medicine to liver biopsy material.

There are many reasons for liver biopsy (Table 1.1), as will be apparent from the contents of this book. Establishing a tissue diagnosis of neoplastic disease, evaluation of jaundice of uncertain cause and assessment of pyrexia of unknown aetiology continue to be common diagnostic problems. Pathologists are well familiar with the need for formal grading and staging of chronic hepatitis (covered in Ch. 9). The ubiquitous ‘elevated liver function tests’ inscribed on biopsy requisitions are now very often explained by steatosis, steatohepatitis or related conditions (Ch. 7) stemming from the wide prevalence of obesity, diabetes, hyperlipidaemia and metabolic syndrome. Indeed, in evaluating abnormal liver function tests in patients with negative serological studies, liver biopsy is rarely normal.⁴ The work-up of liver dysfunction following liver, kidney or haematopoietic cell transplantation is also reliant on information from liver biopsies, which must be reported promptly and with due consideration that the pathological changes in these patients may reflect more than one aetiological factor.

Table 1.1 Reasons for liver biopsy

Type and adequacy of liver biopsy specimen

Several liver biopsy techniques and routes are now available for use (Table 1.2), each with inherent diagnostic advantages and disadvantages.¹ Liver biopsy is an invasive technique which requires a skilled operator and all possible safeguards to minimise the risk of complications. Precise guidelines vary from one centre to another.⁵ Following the biopsy procedure the needle track may be plugged with gelatin sponge (Fig. 1.1) or other materials⁶ (Fig. 1.2) to prevent bleeding.⁷ The standard percutaneous suction needle biopsy popularised by Menghini³ continues to be in active use, while biopsy samples obtained with thin needles under computed tomography guidance and by the transjugular route are now seen more often. Whatever method is chosen, the operator should carefully consider whether the specimen obtained is likely to be adequate for the intended purpose. For example, a small needle specimen obtained with a small-bore needle guided by ultrasound imaging may be adequate for the diagnosis of hepatocellular carcinoma, but not necessarily suitable for the diagnosis and histological evaluation of chronic hepatitis.⁸ With needles of the Menghini type the biopsy core is aspirated and may fragment if the liver is cirrhotic. This is discussed further in Chapter 10. Cutting needles have been reported to produce better specimens,⁹ but in patients with focal lesions aspiration needles often sample both the lesion itself and the adjacent liver; this is helpful in planning treatment.

Table 1.2 Liver biopsy techniques and routes

Figure 1.1 Foreign material.

This is absorbable gelatin which was used to plug a needle track. A small amount of liver tissue is seen at the point of the arrow. (Needle biopsy, H&E.)

Figure 1.2 Foreign material.

Material used to plug a needle track has here escaped and produced a peritoneal foreign-body giant-cell reaction.⁶ (H&E.)

Biopsy pathology differs from autopsy pathology in that there are pitfalls peculiar to small samples. A needle biopsy specimen of liver represents perhaps one fifty-thousandth of the whole organ and there is thus an obvious possibility of sampling error. Some diseases of the liver are diffuse and involve every acinus, so that sampling error is unlikely; these can be diagnosed with confidence even in small specimens. A diagnosis of acute viral hepatitis can be established in a needle specimen only a few millimetres long, whereas a specimen of similar size may not be adequate for the accurate diagnosis and evaluation of chronic liver disease, for assessment of bile duct numbers, for assessing the full extent of steatosis¹⁰ or for the detection of focal lesions such as tumour deposits or granulomas. Focal or unevenly distributed lesions cannot be entirely excluded on the basis of their absence from an unguided needle biopsy specimen. When focal lesions are suspected, multiple biopsies may help to reduce sampling error.

Chronic hepatitis and cirrhosis present particular sampling problems. In some patients with hepatitis there is a zone of extensive necrosis immediately adjacent to the capsule, whereas the deeper parenchyma is less severely affected. A small specimen consisting of tissue from the subcapsular zone of the liver would then give a misleadingly pessimistic impression (Fig. 1.3). In cirrhosis the structure of a nodule is sometimes very similar to that of normal liver, so that a sample consisting almost entirely of the parenchyma from within a nodule may present serious diagnostic difficulties (Fig. 1.4). These are accentuated by the resistance of dense fibrous tissue; in a patient with cirrhosis an aspiration biopsy needle may glance off fibrous septa and selectively sample the softer nodular parenchyma. For this reason, some clinicians prefer to use cutting needles in patients with suspected cirrhosis.¹¹

Figure 1.3 Subcapsular necrosis.

There is a zone of multiacinar necrosis immediately deep to the liver capsule (right) in this patient with chronic hepatitis. The changes are less severe in the deeper tissue to the left. A small superficial sample would have presented problems of interpretation. (Needle biopsy, H&E.)

Related posts:

The Normal Liver Drugs and Toxins Cirrhosis Disturbances of Copper and Iron Metabolism Chronic Hepatitis Neoplasms and Nodules

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