Histopathologic and clinical spectrum of IgA nephropathy coexisting with other glomerulopathies; addressing the diagnostic challenges. Experience from a tertiary care center.

BACKGROUND: Little is known about IgA nephropathy (IgAN) occurring alongside other glomerulopathies. In this study, we aimed to analyze the laboratory and histological spectrum of lesions in such cases and address points which may aid in their diagnosis.

METHODS: This was a retrospective study at a tertiary care center in India, over a 4 year period. Data were gathered and analyzed regarding patients with IgAN occurring concurrently with other causes of glomerulopathies, including podocytopathies, diabetic kidney disease, membranous nephropathy (MN), anti-neutrophil cytoplasmic autoantibody  glomerulonephritis (ANCA-GN), anti-glomerular basement membrane glomerulonephritis (anti-GBM GN), and amyloidosis. Histology was reviewed by two pathologists. Median with interquartile range was used for descriptive data and compared using the Mann-Whitney U-test, apart from age for which mean with standard deviation (SD) was used and compared using Chi-square/Fisher's exact tests.

RESULTS: Out of 1716 cases diagnosed with IgAN, 82 (4.7%) were found to have co-existing glomerulopathies. IgAN patients with podocytopathy were the youngest, with a mean age of 27.33 (± 14.56) years, with mesangial hypercellularity and segmental sclerosis being the most common lesions. IgAN with diabetic glomerulopathy most often affected older individuals, with a mean age of 51.50 (± 9.82) years. Patients with IgAN and either ANCA-GN or anti-GBM GN had the highest percentage of interstitial fibrosis and tubular atrophy (IFTA), and crescents. There were two cases only of concomitant AA amyloidosis.

CONCLUSION: In case of IgAN with atypical or complex presentation, rapidly deteriorating kidney function, other co-existing glomerular pathologies should be ruled out, as these may require treatment modification.