short-coming of liver biopsy, particularly when done by radiologists, or in the setting of bariatric
surgery, is the use of appropriately sized (i.e., large-bore) needles, [6], and potential differences between
the right and left lobes of the liver. For instance, the subcapsular portal tracts in the left lobe are larger
and closer to the capsule than in the right lobe; if not aware of this, a pathologist can misinterpret the
seemingly enlarged portal structures from a left lobe biopsy for fibrotic portal structures, particularly
if a small bore needle has been used to obtain the biopsy. Determining histologic inflammation in
the liver parenchyma will not lead to valid results from a biopsy obtained in a surgical procedure,
as anesthesia alone will lead to parenchymal and perivenular collections of polymorphonuclear
leukocytes, collectively known as “surgical hepatitis”. Discerning which foci were present prior to
anesthesia, and which are due to surgical hepatitis is not possible. Further, if a study protocol includes
biopsy, agreement of exact location should be made in advance with all investigators so that pre and
post intervention biopsies are truly comparable. Finally, the interpreting pathologist’s expertise and
familiarity with the spectra of lesions in the disease process are factors to be considered in NAFLD, as
in any other form of liver disease [7,8].
Once the decision for liver biopsy has been made, whether for clinical (i.e., diagnostic or
prognostic) purposes, or for clinical trial protocol, the next steps involve the histopathologic
interpretation for diagnosis, and for semi-quantitative lesion evaluations, if requested, for protocol or
study purposes. Methods for these are the subjects of the remainder of this review.