Definition [3, 4, 5]The definition is histopathologic with the characteristical deposition of the immunoglobulin A in the renal mesangium: these deposits are predominant (or codominant with other immunoglobulins, IgG and/or IgM), granular, coarse (with the "en mottes" aspect), generalized in the glomerulus and diffuse to all glomeruli. These deposits are evidenced usually by the technique of direct immunofluorescence on a semi-quantitative scale: traces (+/-), 1+, 2+, and ≥ 3+. There is a general agreement to accept at least 1+ IgA deposits for the definition. By contrast, the lesions observed by light microscopy are often segmental and focal. The main lesions concern the mesangium with increased matrix and hypercellularity with in addition endocapillary proliferation. The most severe lesions are represented by obsolescent glomeruli ("pains à cacheter"), focal and segmental glomerulosclerosis (FSGS) with capsular adhesions, and extracapillary proliferation with the formation of cellular/hyalinized crescents.
The IgA nephritides [3, 4, 5]
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.