Clinicopathologic Features of IgA-Dominant Postinfectious Glomerulonephritis.

Background: IgA-dominant acute postinfectious glomerulonephritis (APIGN) is a recently recognized morphologic variant of APIGN, but its clinicopathologic features were not clearly characterized. We will present demographic, clinical and renal biopsy findings from seven patients with IgA-dominant APIGN with a literature review.

Methods: All renal biopsy specimens (n=1,119) processed by the Department of Pathology in Hanyang University Hospital from 2005 to 2009 were reviewed. Seven patients with IgA-dominant APIGN were identified, and their clinical data analyzed.

Results: All patients had renal failure, hematuria and proteinuria. One was diabetic, and none of the patients had previous renal diseases. Three had clinical infections at the time of presentation: 2 with methicillin-resistant Staphylococcus aureus and one with rickettsial infection. Light microscopically diffuse endocapillary proliferative and exudative glomerulonephritis was found in all cases. Immunofluorescence microscopy showed granular IgA deposits along peripheral capillary walls and in mesangium. Ultrastructurally, subepithelial 'humps' with mesangial deposits were noted. End-stage renal disease developed in two patients, chronic renal failure was stationary in two, and azotemia improved in three.

Conclusions: Various infections including rickettsiosis preceded IgA-dominant APIGN in both diabetics and nondiabetics. Because the prognosis of IgA-dominant APIGN is poor, early diagnosis based on renal biopsy is required.