The pathology of cholestasis.

Hepatic formation of bile is critical to survival and is one of the most easily disrupted liver functions. Liver biopsy is performed to obtain a definitive diagnosis of cause, to exclude potential etiologies, or simply to assist in development of a differential diagnosis. Parenchymal changes of cholestasis (feathery degeneration of hepatocytes, dilated bile canaliculi with retained bile, Kupffer cell phagocytosis of bile that has leaked into the sinusoidal space) are nonspecific and may be seen with both nonobstructive and obstructive cholestasis. The portal tract changes of obstruction are characteristic: bile ductular proliferation, inspissated bile in bile ducts, portal tract edema, neutrophilic inflammation, and cholate stasis of periportal hepatocytes. Uncorrected obstruction incites robust fibrogenesis by portal tract myofibroblasts, engendering a characteristic jigsaw pattern of fibrous septa. Diseases with specific histological features include primary biliary cirrhosis, primary sclerosing cholangitis, biliary atresia, and graft-versus-host disease. However, the pathologist is cautioned not to overinterpret the cholestatic liver biopsy and to apply rigorous criteria for specific causal diagnoses. Most of the histological features of cholestasis are nonspecific. Hence, both practicing physician and pathologist should have sound knowledge of the pathology of cholestasis.