Background and aims Raising evidence supported a prognostic utility of tubulointerstitial lesions in lupus nephritis (LN). The exact prevalence of tubulointerstitial abnormalities and its predictive value among paediatric onset systemic lupus erythematous (pSLE) cases, however, remained unknown.

Methods Sixty-seven pSLE subjects diagnosed with LN with initial renal samples available were enrolled and followed for an average of 6.43±3.06 years. Renal histology was evaluated according to the International Society of Nephrology/Renal Pathology Society classification, National Institute of Health classification and tubulointerstitial activity index (TIAI).

Results Tubulointerstitial injuries were observed in 38.81% of all LN cases, including 13.33% with non-proliferative lupus nephritis (nPLN) and 46.15% of with proliferative lupus nephritis (PLN). Tubulointerstitial injuries occurred solitarily in cases with nPLN(13.33%), but always associated glomerular changes and significantly impacted renal survival (p=0.032) among those with PLN. TIAI associated glomerular abnormalities (p=0.031) but did not correlate renal performance or subsequent outcome (p=0.445). Among the chronicity index, it was the chronic tubulointerstitial lesions which provided prognostic information (p=0.012). We observed a synergistic effect of all tubulointerstitial abnormalities rather than an individual factor attributed the prognostic utility (p=0.025 vs. p=0.083, 0.055, 0.354). Finally, considering tubulointerstitial injuries in PLN further discriminated subsequent renal outcome (p=0.006).

Conclusions The prevalence and clinical significance of tubulointerstitial abnormalities were similar among the pSLE and the adult population. With its importance in identifying those at risk of renal failure, histologic classification considering tubulointerstitial lesions may potentially assist outcome prediction.