The accuracy of Masson's trichrome stain in predicting the presence or absence of glomerular immune complexes.

The accuracy of Masson's trichrome stain to predict the presence of immune complexes was determined in 63 renal biopsies. When immunofluorescence was defined as the reference method, the histologic method correctly predicted the presence or absence of deposits in 70% of biopsy specimens, while electron microscopy was accurate in 79% of specimens. This difference was not statistically significant. The commonest error in our assessment of the Masson's trichrome-stained specimens was the erroneous interpretation of specimens showing minimal change nephropathy or ischemic glomerulopathy by immunofluorescence and electron microscopy. This resulted in a falsely positive diagnosis of one or another of the glomerulonephritides in 13% of cases. Thus, the routine study of renal biopsies with Masson's trichrome stain is clearly useful and should be applied with caution, but it does not replace electron-microscopic and immunofluorescence studies.