Quantitative measurement of fibrosis in pancreatic tissue. Evaluation of a colorimetric method.

A colorimetric method has been used to quantify the collagen contained in 23 specimens of pancreatic tissue (11 controls and 12 chronic pancreatitis). The method takes advantage of the selective capacity of Sirius red to stain collagen protein and of rapid green to stain noncollagen protein. The results obtained by this method were compared with those of standard morphometry to determine tissue fibrosis. With the morphometric method, the values of the control group were 6.6 +/- 4.0% (fiber area/total area), and those of chronic pancreatitis 66.0 +/- 19.0% (difference 59.4, 95% confidence interval for difference: 47.2-71.6, P less than 0.001). The values obtained with the colorimetric method were 89.1 +/- 11.6 micrograms collagen/mg total protein in the control group, and 132.7 +/- 25.3 micrograms collagen/mg total protein in the chronic pancreatitis group (difference 43.6, 95% confidence interval for difference: 26.3-61.0, P less than 0.001). A highly significant correlation (r = 0.847; p less than 0.001) was observed between the amount of collagen measured colorimetrically and the degree of fibrosis determined morphometrically. These results demonstrate that the colorimetric method is a reproducible, simple, and rapid technique to quantitate fibrosis in histological preparations of pancreatic tissue.