Clinical and pathohistological characteristics of lupus nephritis in pediatric and adult population

Introduction: Systemic lupus erythematosus (SLE) is an autoimmune disease, characterized by abundant production of antibodies, deposits of immune complexes, and activation of the complement system, which disrupts the integrity and function of many organs, including the kidney. Although the frequency of SLE is less common in children, affected children develop lupus nephritis (LN) significantly more often, while in adults with SLE, LN occurs in 23% of cases, more often in males. Aim: The aim of this study was to analyze clinical parameters (gender, frequency of LN as the first manifestation of SLE, proteinuria, and serum creatinine values) and pathohistological parameters (frequency of LN classes, activity and chronicity index values, immunoglobulin deposit intensity and complement components at immunofluorescence, and blood vessel lesions) in the pediatric and adult populations of LN patients. Material and methods: The study included 218 biopsy samples of kidney tissue. Patients were divided into two groups: patients under 18 years of age (n=35) and those over 18 years of age (n =183). Results: Mean values of serum creatinine in pediatric population (71.6±16.4 µmol/l) were statistically significantly lower (p<0.001) than in adults (115.5 ±64 µmol/l). Leukocyte interstitial infiltration was statistically significantly higher in the adult group (p=0.003). The average value of the chronicity index (p=0.002), as well as the tubulointerstitial parameters that determine it (tubular atrophy (p <0.001) and interstitial fibrosis (p=0.011)) were significantly higher in adults with LN. Leukocyte infiltration (p=0.003) and myoelastofibrosis (p<0.001) of blood vessels were statistically significantly more common in the adult population. Conclusions: Serum creatinine values are significantly higher in the adult population of LN. Pathohistological findings indicate that glomerular LN lesions do not differ significantly with regard to activity and chronicity index in pediatric and adult populations, but the degrees of tubulointerstitial lesions are significantly higher, both in terms of activity and in terms of chronicity within the adult groups. Myoelastofibrosis and hyalinization of blood vessels as well as leukocyte infiltration of blood vessels, are statistically significantly more common in the adult population.