Clinical, laboratory, and pathological correlates of crescent formation in biopsy-proven pediatric IgA vasculitis nephritis.

BACKGROUND

Crescent formation is common in pediatric IgA vasculitis nephritis (IgAVN), but its clinicopathological correlates and the significance of crescent burden and activity remain unclear.

METHODS

We retrospectively analyzed 1,280 children with biopsy-proven IgAVN and available crescent assessment who were hospitalized at the Department of Pediatric Nephrology, The First Affiliated Hospital of Henan University of Chinese Medicine, between January 2013 and January 2021. Patients were classified by the presence or absence of crescents on kidney biopsy. Univariable and sequential multivariable logistic regression analyses were performed, with additional stratified, post hoc, and sensitivity analyses for crescent burden and active crescents.

RESULTS

Crescent formation was identified in 903/1,280 children (70.5%). Compared with those without crescents, children with crescents were older and more likely to have gross hematuria, gross gastrointestinal bleeding, at least one non-cutaneous extrarenal manifestation, and severe renal clinical involvement. They also had higher 24-h urinary protein excretion and D-dimer levels and more frequent active and chronic pathological lesions. In the fully adjusted model, glomerulosclerosis, tubulointerstitial fibrosis, tubulointerstitial inflammation, endocapillary hypercellularity, and glomerular necrotizing lesions remained independently associated with crescent formation. Higher crescent burden was associated with heavier proteinuria, higher D-dimer levels and more frequent active and chronic pathological lesions. In sensitivity analyses, tubulointerstitial inflammation and glomerular necrotizing lesions remained consistently associated across alternative crescent-related outcomes.

CONCLUSIONS

In children with IgAVN, crescent formation is associated with a more severe clinicopathological phenotype and should be interpreted in the context of coexisting active and chronic kidney lesions. Kidney biopsy remains essential for defining crescent-related lesions.