THE NORMAL ADULT HUMAN LIVER-BIOPSY - A QUANTITATIVE REFERENCE-STANDARD

In assessing adult human liver histology, questions remain concerning the normal number of portal tracts and bile ducts in a liver biopsy. W e therefore reviewed liver biopsies obtained with use of a percutaneou s Menghini cutting needle (14G, internal diameter 1.6 mm), from 16 pat ients undergoing liver biopsy for screening procedures (age 49 +/- 14 years, +/- SD) and found to be normal by histological examination. The average aggregate length of the liver tissue was 1.8 +/- 0.8 cm (area of 16.4 +/- 10.7 mm<SUP>2</SUP>), representing 7 +/- 3 tissue fragmen ts. Portal triads containing at least one profile each of a portal vei n, hepatic artery, and interlobular bile duct numbered 11 +/- 6 per bi opsy (range 3-23), Portal dyads, which did not contain one of these pr ofiles, usually the portal vein, numbered 8 +/- 5 (range 1-18), On a p er-specimen basis, 38% of portal tracts did not contain a portal vein, 7% did not contain a bile duct, and 9% did not contain a hepatic arte ry. Because of multiplicity of profiles within portal tracts, however, the average number of profiles per portal tract was 6 +/- 5 (range 2- 35). Notably, on average there were 2.3 +/- 2.2 interlobular bile duct s per portal tract, compared to 2.6 +/- 2.3 hepatic arteries and 0.7 /- 0.7 portal veins. The average minimum external diameter of interlob ular bile ducts was 13 +/- 4 mu m, of hepatic arteries 12 +/- 5 mu m, and of portal veins 34 +/- 25 mu m. Bile ducts greater than 30 mu m in diameter were rare, only one each in two biopsies were observed. In c ontrast, probable canals of Hering were occasionally evident at the pe riphery of portal tracts (6 +/- 6 per biopsy) and within the lobular p arenchyma as strings of cuboidal cells (5 +/- 5 per biopsy). We conclu de that, although multiplicity of profiles is normal, portal dyads are almost as common as portal triads in normal peripheral liver tissue. On average, there are two interlobular bile ducts, two hepatic arterie s, and one portal vein per portal tract, with 6 full portal triads per linear cm of tissue obtained by external Menghini biopsy technique wi th use of a 14G needle, equivalent to 0.8 +/- 0.5 portal triads per mm <SUP>2</SUP>.<SUP></SUP> By serving as a reference standard for adult human liver histology, these findings may assist in the histopathologi cal assessment of liver biopsies, particularly those performed for dis ease conditions featuring loss of intrahepatic bile ducts.