Abstract
Nonalcoholic fatty liver disease (NAFLD) results in histologically complex specific
and nonspecific injury patterns. In clinical research of NAFLD, the liver biopsy evaluation
provides a wealth of information on the architectural arrangement and severity of
a variety of histologic changes, including steatosis, inflammation, cellular injury,
and fibrosis. This information is summarized as an overall diagnostic category, such
steatosis or steatohepatitis and the severity of the injury can be graded and staged.
Histopathologic disease classification in NAFLD is related to but separate from evaluation
of individual histologic lesions. The patient population under study may affect the
prevalence of histologic findings and in particular, pediatric patients with NAFLD
may show a higher prevalence of zone 1 steatosis and periportal fibrosis as compared
with adult populations. For the purposes of clinical research, it is important to
provide the pathologist with biopsies that are adequate to classify the disease process
as well as to grade and stage the changes. A current understanding of NAFLD pathologic
classification, as well as nuances of grading and staging, is presented in this review.
Keywords
Bariatric surgery - disease classification - lipodystrophy - liver biopsy - nonalcoholic
fatty liver disease - pediatric fatty liver disease - steatohepatitis - steatosis
