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Chronic hepatitis represents a series of liver disorders of varying causes and severity in which hepatic inflammation and necrosis continue for at least 6 months. Milder forms are nonprogressive or only slowly progressive, while more severe forms may be associated with scarring and architectural reorganization, which, when advanced, lead ultimately to cirrhosis. Several categories of chronic hepatitis have been recognized. These include chronic viral hepatitis, drug-induced chronic hepatitis (Chap. 333), and autoimmune chronic hepatitis. In many cases, clinical and laboratory features are insufficient to allow assignment into one of these three categories; these “idiopathic” cases are also believed to represent autoimmune chronic hepatitis. Finally, clinical and laboratory features of chronic hepatitis are observed occasionally in patients with such hereditary/metabolic disorders as Wilson’s disease (copper overload), α1 antitrypsin deficiency (Chaps. 337 and 408), and nonalcoholic fatty liver disease (Chap. 336) and even occasionally in patients with alcoholic liver injury (Chap. 335). Although all types of chronic hepatitis share certain clinical, laboratory, and histopathologic features, chronic viral and chronic autoimmune hepatitis are sufficiently distinct to merit separate discussions. For discussion of acute hepatitis, see Chap. 332.
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CLASSIFICATION OF CHRONIC HEPATITIS
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Common to all forms of chronic hepatitis are histopathologic distinctions based on localization and extent of liver injury. These vary from the milder forms, previously labeled chronic persistent hepatitis and chronic lobular hepatitis, to the more severe form, formerly called chronic active hepatitis. When first defined, these designations were believed to have prognostic implications, which were not corroborated by subsequent observations. Categorization of chronic hepatitis based primarily on histopathologic features has been replaced by a more informative classification based on a combination of clinical, serologic, and histologic variables. Classification of chronic hepatitis is based on (1) its cause; (2) its histologic activity, or grade; and (3) its degree of progression based on level of fibrosis, or stage. Thus, neither clinical features alone nor histologic features—requiring liver biopsy or noninvasive markers of fibrosis—alone are sufficient to characterize and distinguish among the several categories of chronic hepatitis.
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CLASSIFICATION BY CAUSE
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Clinical and serologic features allow the establishment of a diagnosis of chronic viral hepatitis, caused by hepatitis B, hepatitis B plus D, or hepatitis C; autoimmune hepatitis, including several subcategories, I and II, based on serologic distinctions; drug-associated chronic hepatitis; and a category of unknown cause, or cryptogenic chronic hepatitis (Table 334-1). These are addressed in more detail below.
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