[1522] Focal Segmental Glomerulosclerosis and Extra Efferent Vessel Development in IgA Nephropathy

BJ Lim, HJ Jeong. Yonsei University College of Medicine, Seoul, Korea

Background: Segmental glomerulosclerosis (SGS) is not infrequently observed in advanced stage of IgA nephropathy (IgAN) with severe mesangial/endocapillary proliferation or interstitial fibrosis. However, the morphology and pathogenetic mechanisms have not been clearly demonstrated in cases showing mild glomerular and tubulointerstitial changes.
Design: To explore the evolution of SGS in this condition, we selected 62 cases of IgAN with focal SGS, which did not demonstrate significant mesangial or endocapillary proliferation or tubulointerstitial fibrosis (Hass subclass II). Each segmentally sclerotic glomerulus was traced in more than 20 serial sections and SGS was subtyped as classic, perihilar, tip, cellular, and collapsing variant. These data were correlated with other histologic and clinical parameters.
Results: SGS was present 2.6% to 45.5% of glomeruli in each case. Among the five subtypes, tip variant was the most common (31 cases) followed by classic type (29 cases) and perihilar variant (12 cases). Neither cellular nor collapsing forms were present. Adhesion of capillary loops was present in almost all cases. Most of the tip lesions appear to be similar to glomerular scar associated with sclerosing capillaritis. Interestingly, we observed extra-efferent vessels situated away from vascular hilum, which communicated glomerular capillaries and extraglomerular capillaries through gaps in Bowman's capsule, a phenomenon which has not been reported in literature previously.

Conclusions: SGS is not infrequent even in IgAN with mild glomerular histology. Most of the SGS seem to result from capillary endothelial injury. However, it should be further clarified on the mechanisms of formation of extra-vessels through gaps in Bowman's capsule in IgAN.
Category: Kidney (does not include tumors)

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 238, Wednesday Afternoon


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