Clinicopathologic features in childhood-onset lupus nephritis with antineutrophil cytoplasmic antibody positivity--a multi-center retrospective study.

Background: Positive antineutrophil cytoplasmic antibody (ANCA) serology in adult-onset lupus nephritis (LN) is associated with more active disease and distinct renal pathology, but data with respect to childhood-onset LN remain scarce. Here, we aimed to determine the impact of positive ANCA serology on clinical and histopathologic features and renal outcomes in children with LN from multiple centers.

Methods: Clinical and histopathologic data of 61 ANCA-positive and 330 ANCA-negative LN children (1
Results: Among 61 ANCA-positive LN children, 86.9% of them had antimyeloperoxidase antibodies. Both ANCA-positive and ANCA-negative children had high disease activities with median SLEDAI-2K of 16 (13, 20). Hematuria was more prominent (urinary RBC +++ ∼ ++++: 45.9% vs 26.7%, = 0.011), while fever (42.6% vs. 58.2%, = 0.035), alopecia (3.3% vs. 14.5%, = 0.019), photosensitivity (0% vs. 8.2%, = 0.013), and pleurisy (4.9% vs. 15.8%, = 0.026) were less common in ANCA-positive children. Higher proportions of segmental sclerosis (23.7% vs. 9.8%, = 0.025), crescentic formation (36.4% vs. 16.3%, = 0.009), and capillary wall thickening (24.5% vs. 11.0%, = 0.01) were observed in biopsies of ANCA-positive children. Long-term renal survival did not differ significantly between two groups ( = 0.300).

Conclusions: Positive ANCA serology in LN children was associated with different clinical and histopathologic features compared to those with negative ANCA serology. Further studies are needed to clarify the pathogenic role of ANCAs in childhood-onset LN and confirm their association with prognosis.