Spectrum of Renal Histopathologic Lesions in Patients with Nonlupus Rheumatologic Diseases

Background: Nonlupus rheumatic diseases regularly involve solid organs, including the kidney. Renal lesions can be either a manifestation of the same systemic disease, a side effect of drug therapy, or an unrelated renal disease. Our aim was to evaluate the spectrum of renal histopathological lesions found in this group of patients. Methods: Native renal biopsies of patients with systemic rheumatic disorders received between January 2014 and August 2019 were reviewed, along with their immunofluorescence findings. The clinical data were recorded from the Hospital Information System. Patients with systemic lupus erythematosus were excluded. Results: Eighty-one clinically diagnosed cases of nonlupus rheumatic diseases were studied (age range 8-70 years, mean 42.8 years, male: female ratio 1:1.3). The most common systemic autoimmune disease was anti-neutrophil cytoplasmic antibodies -associated vasculitis (n = 21) followed by immunoglobulin-A (IgA) vasculitis (Henoch-schonlein purpura) (n = 12) and rheumatoid arthritis (n = 10). The most common histopathological lesion was pauci-immune crescentic glomerulonephritis (n = 26), followed by IgA nephropathy (n = 12) and amyloidosis (n = 8). All patients were treated as per the standard therapeutic regimens. Conclusion: A diverse group of renal lesions can be found in patients with rheumatic disorders. The diagnosis of such lesions aids the clinician in the decision-making for either intensifying or reducing the drug therapy and in predicting the prognosis.