Correlation of E1 lesions and CD68 count with proteinuria and clinical outcome in IgA nephropathy

Background: IgA nephropathy (IgAN) has variable course; few patients have a benign presentation and other patients present with late stage disease. Endocapillary hypercellularity has a prognostic significance in IgAN. It is important to identify E1 lesions accurately. The use of CD68 immunohistochemistry marker to identify glomerular macrophages will standardize the reporting and help the clinicians prognosticate the patients. Subjects and Methods: The material is from a referral laboratory for renal biopsies in a tertiary care hospital. Renal biopsies are processed as per protocol including light microscopy, immunofluorescence and electron microscopy where ever required. CD68 was used in this study to identify macrophages in E1 lesions. A total of 1220 primary glomerular diseases were diagnosed from January 2019 till date. Out of these, IgA constituted 11.9% of primary glomerular diseases. Renal biopsies received were from the department of nephrology and various other nephrology centers. Biopsies were received in 10% buffered formalin. Immunofluorescence is done on all biopsies, and electron microscopy was done in few cases to differentiate from other lesions with dominant IgA deposits. CD68 was done in 50 cases of IgAN. Apart from hematoxylin and eosin stains, periodic acid-Schiff, Masson trichrome, Jones silver stain were also done. Results: IgAN constituted 11.9% of cases. Twenty-five cases of E0 and twenty-five cases of E1 lesions were correlated with clinical and morphological features. There was correlation with proteinuria and hypertension in E1 lesions. There was no significant correlation with the morphological variants like crescents, focal segmental glomerulosclerosis. Conclusions: Inter observer correlation of E lesions is poor in classifying IgAN. Use of CD68 is a useful adjunct to identify macrophages. E1 lesions have more proteinuria requiring treatment for delaying the progression to end stage disease. Despite significant association of E1 lesions with progression, there may be many unmeasured factors which would influence the outcome.