Proliferative glomerulonephritis (GN) is defined as an increase in glomerular cellularity due to the influx of leukocytes and/or the proliferation of native cells. There are four major light microscopy patterns of proliferative GN – mesangial, endocapillary, membranoproliferative, and crescentic/necrotizing (extracapillary). Diagnosis requires the correlation of the injury pattern seen by light microscopy (LM) with the nature and localization of deposition, often immune complexes (IC) that are the cause of that injury found on immunofluorescence microscopy (IF). While certain LM patterns may be associated with corresponding IF patterns, there is substantial variation and even evolution as the disease progresses. In a recent AJKD Perspective, Dr. Sethi proposes an interesting new classification of proliferative GN that correlates the findings from both LM and IF, but classifies proliferative GN primarily on the basis of the IF findings into three groups: IC/Ig-mediated, pauci-immune, and complement (ie, C3) based. As he states, this is similar to our current classification of crescentic GN. Each of the three groups is further classified by 1) dominant Ig and/or complement factor, 2) LM injury pattern, and 3) presumed cause of the disease process. The author argues that this new classification will better focus on the underlying pathophysiology and cause of the GN, thus directing the clinician to appropriate evaluation and management of proliferative GN. In the quiz below, we test your ability to interpret the LM and IF patterns illustrated, and the understanding of the disease processes most commonly associated with these lesions.
Below find five LM images of proliferative GN. Match each injury pattern with their most commonly associated IF pattern from among the available choices (hint: each image is used once)!
Click on an image for a larger view.
Post prepared by and all images courtesy of Isaac E. Stillman, MD, eAJKD Contributor and AJKD Kidney Biopsy Teaching Case Advisory Board member.
To see answers, please click here.