The type of interstitial inflammatory cell infiltrate and the severity of glomerular injury; an underestimated morphologic correlation

Introduction: The interrelation between the type of interstitial inflammatory cells and the severity of glomerulonephritis was not considered in most of the relevant medical literature. Objectives: To investigate the relationship between the type of interstitial cell infiltrate and the morphological severity of glomerular injury in different types of proliferative glomerulonephritides. Patients and Methods: We retrospectively reviewed 138 native kidney biopsies and assessed the relationship between the type of interstitial inflammatory cell infiltrate and the severity of glomerular injury in the form of cellular crescents and fibrinoid necrosis. Results: The predominant type of interstitial inflammatory cell infiltrate was lymphocytic, noted in more than half of the cases. Lymphoplasmacytic inflammatory cell infiltrate was the second most common type which observed. Fifty-five of patients had inflammation in areas of fibrosis. Cellular/fibrocellular crescents were observed in 44% of cases, and fibrinoid necrosis in 30% of cases. As compared to the ‘lymphocytic’ group, patients in the ‘lymphoplasmacytic’ group had ~3 times higher probability of presenting with crescents and fibrinoid necrosis. Conclusion: Our study highlights the significance of morphological correlations that may predict the severity of glomerular injury. Such findings would be helpful in limited or inadequate renal biopsy samples where the pathologist can alert the clinician, in the appropriate clinical context, to the possibility of having crescents and/or necrotizing lesions in the unsampled glomeruli.