Electron microscopic findings

Abstract

In IgG4-related kidney disease, there has been broad recognition that the basic renal manifestation of IgG4-related disease is tubulointerstitial nephritis characterized by copious plasma cell infiltrates. In some cases changes are also observed in the glomeruli, showing most frequently a histological change similar to that of membranous glomerulonephritis. Ever since this disease concept was first proposed, the histopathology of renal biopsy specimens has been actively investigated, but most such studies have relied on light microscopy, and detailed electron microscopic studies focused on the interstitial changes have not yet sufficed. Electron microscopic analysis of the changes remains of extreme importance in elucidating the pathophysiology and true nature of this disease. The unusual interstitial change which is designated as “storiform fibrosis” or “bird’s eye pattern fibrosis” by light microscopy, is actually not simple fibrosis but “fibrosing sclerosis” by electron microscopic observation. In this chapter, the electron microscopic findings of this disease thus far clarified are outlined, and in addition mention is made of some of the issues that remain to be addressed in future work.