Renal biopsy pathology in a cohort of patients from southwest Sydney with clinically diagnosed systemic lupus erythematosus

Jim LC Yong,^1,2 Murray C Killingsworth,^1–3 Ken Lai<sup>1,2

1</sup>Department of Anatomical Pathology, Sydney South West Pathology Service, ²University of Western Sydney, School of Medicine, 3University of New South Wales, Faculty of Medicine, Sydney, New South Wales, Australia

Purpose: The pathological manifestations in the kidneys in systemic lupus erythematosus (SLE) are commonly known as lupus nephritis. We have studied the pathological changes in renal biopsies from 59 cases of clinically diagnosed SLE obtained over a 15-year period from a racially diverse population in the Sydney metropolitan area. Our aim was to see if there was any regional variation in the morphological changes.
Methods: Renal biopsy changes were assessed by routine light, immunofluorescence, and electron microscopy. We used the modified 1974 World Health Organization classification of lupus nephritis to classify cases into six classes. Disease severity was assessed by age, sex, and across racial groups, including Caucasian, Asian, Middle Eastern, Mediterranean, Indian subcontinental, South American, and Pacific Islander.
Results: Our analysis showed that cases of lupus nephritis contributed 5.4% of our total renal biopsies examined over a 15-year period. The overall incidence of biopsy-proven cases was 0.49 per 100,000 per year. The ages of our patients ranged from 10 to 79 years, with most below 50 years of age. A female to male ratio was determined to be 4.4:1. There was no relationship to ethnicity, nor was there a relationship between any of these parameters and the class or severity of disease.
Conclusion: Renal biopsy with multimodal morphological and immunohistochemical analysis remains the gold standard for diagnosis and determination of the level of disease in lupus nephritis. Based on this approach we have identified an incidence rate for southwest Sydney that is slightly higher but comparable to that found in a similar study from the United Kingdom. We also found that there was no relationship between sex, race, or age and severity of disease.

Keywords: systemic lupus erythematosus, SLE, lupus nephritis, histology, immunohistochemistry, electron microscopy