Pathomorphological characteristic of IgG4-related diseases

Abstract

IgG4-related diseases are a relatively new group of diseases of unknown etiology which are characterized by the development of fibrosis of organs with the presence of big amounts of IgG4-positive plasma-cells in the area of the lesions and increased levels of IgG4 in serum. The organs that may be affected are pancreas, salivary gland, and others, clinical cases of kidney damage are described as well. Renal involvement in IgG4-related diseases most often occurs on the type of tubulointerstitial nephritis, with the further development of acute or chronic kidney injury. The clinic may be represented by the pseudotumor of kidney, renal tissue heterogeneity on the results of CT-studies; acute or chronic renal disease; combination with other organ damage (autoimmune pancreatitis, sclerosing cholangitis, sclerosing lymphoplasmacytic cholecystitis, colitis, sialadenitis, retroperitoneal fibrosis, etc.). Laboratory findings include an increased level of IgG4 in the blood serum, hypocomplementemia, eosinophilia. Histologically, there is interstitial inflammation with many plasma cells, interstitial fibrosis, tubular atrophy, thickening of the tubular basement membrane, some cases are a type of membranous glomerulonephritis. The aim of the study is to identify the patients with IgG4-related diseases with renal impairment and widening the pathological database of such patients with renal impairment to determine the classification criteria of this pathological condition. Materials and methods will include the deceased kidney screening, screening of patients with autoimmune and allergic diseases, nephrological patients screening with the lifetime biopsy (in some cases – repeat biopsy) with chronic or acute kidney impairment. There will be clinical and pathological comparison in kidney damage and other diseases with the development of criteria for the classification of lesions in the presence of IgG4-positive substrates and further development of practical recommendations for the timely diagnosis of IgG4-related diseases. Results. We already performed a retrospective analysis of 162 kidney biopsies in which, in 13 cases (8%) we noted abnormal IgG4-positive plasma cells deposition and other unspecific, but typical morphological signs of the disease. Conclusions. The identification of IgG4 marker can favor of presence of IgG4- related disease. The creation of pathological register of IgG4-related diseases is important for the accurate diagnosis and the development of criteria for classification of IgG4-related diseases.