IgG4-RD can affect almost all organs in the body, and each affected organ has common histopathological features of lymphoplasmacytic infiltration with characteristic fibrosis called storiform fibrosis. In particular, dense IgG4-positive plasma cell infiltration is a hallmark of this disease. Clinical features include a male and middle- or old-age predominance, Pexidartinib ic50 hypergammaglobulinemia and elevated serum IgG4 levels. In our experience of 74 cases, frequently affected organs were salivary glands (55%), lacrimal glands and other ophthalmic components (54%), lungs (31%), kidneys (26%), aorta/periaorta (24%), and pancreas (20%). Lymphadenopathy was

also noted (27%). IgG4-RD is sometimes asymptomatic or tends to cause relatively mild clinical symptoms. Coexistent autoimmune disease is rare, and rather it has a close association with allergic disorders such as allergic rhinitis and bronchial asthma. Although IgG4-RD is

a steroid responsive condition, delayed diagnosis and treatment result in irreversible fibrosis. In this overview, I will outline this systemic disease including some up-to-date topics of particular interest. NAGATA MICHIO1,2 HARA SATOSHI1,3 MIZUSHIMA ICHIRO3 KAWANO MITSUHIRO2,3 SAEKI TAKAKO2 UBARA YOSHIFUMI2 OHARA NOBUYA2 SATO YASUHARU2 YAMADA KAZUNORI3 NAKASHIMA HITOSHI2 NISHI SHINICHI2 YAMAGUCHI YUTAKA2 HISANO SATOSHI2 YAMANAKA NOBUAKI2 SAITO TAKAO2 1Department of Kidney and Vascular Pathology, University GSK-3 cancer of Tsukuba, Japan; 2′IgG4-related Kidney Disease’ working group, Japan; 3Department of Rheumatology, Kanazawa Graduate School of Medicine, Japan Patients with IgG4 related systemic disease often complicate renal dysfunction. Among several characteristic features in IgG4-related kidney disease, tubulointerstitial nephritis is the most responsible for renal dysfunction. We have summarized distinctive features of tubulointerstitial lesions

in IgG4-related CYTH4 TIN, i.e., (1) well-demarcated borders between involved and uninvolved areas; (2) involvement of the cortex and medulla, often extending beyond the renal capsule and with occasional extension to retroperitoneal fibrosis; (3) interstitial inflammatory cells comprising predominantly plasma cells and lymphocytes, with a high prevalence of IgG4-positive cells often admixed with fibrosis; (4) peculiar features of interstitial fibrosis resembling a “bird’s-eye” pattern comprising fibrosis among inter-plasma cell spaces; and (5) deposits visible by light and immunofluorescent microscopy in the tubular basement membrane, Bowman capsule, and interstitium that are restricted to the involved portion, sparing normal parts. Ultrastructural analysis revealed the presence of myofibroblasts with intracellular/pericellular collagen accompanied by plasma cell accumulation from an early stage. As such lesion is depending on the stage and extension, renal biopsy samples contains limited information to assess background pathophysiology.