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Abstract: SA-PO344

PLA2R Expression in Pediatric Membranous Nephropathy: A Multi-Institution Retrospective Study

Session Information

Category: Glomerular Diseases

  • 1202 Glomerular Diseases: Immunology and Inflammation

Authors

  • Delsante, Marco, Johns Hopkins Hospital, Baltimore, Maryland, United States
  • Allinovi, Marco, Meyer Children's Hospital, Firenze, Italy
  • Kwon, Donghyang, Georgetown University Hospital, Washington, District of Columbia, United States
  • Conces, Miriam, Nationwide Children's Hospital, Columbus, Ohio, United States
  • Mazzinghi, Benedetta, Meyer Children's Hospital, Firenze, Italy
  • Alzarka, Bakri, Children's National Medical Center, Washington, District of Columbia, United States
  • Kallakury, Bhaskar, Georgetown University Hospital, Washington, District of Columbia, United States
  • Rosenberg, Avi Z., Johns Hopkins Hospital, Baltimore, Maryland, United States
Background

Membranous nephropathy (MN) is a rare cause of nephrotic syndrome in children and can be idiopathic (IMN) or secondary to systemic diseases (i.e. SLE, chronic infections and malignancy). In adults with IMN, antibodies against phospholipase A2 receptor (PLA2R) are present in 57-82% of patients and expression of PLA2R is increased in glomeruli by histochemical staining. The latter is a useful diagnostic tool allowing the pathologist to suggest an idiopathic versus secondary process. However, PLA2R expression in children with MN has not been studied in large cohorts, and small case series have shown lower sensitivity (6-45%) compared to adults.

Methods

We retrospectively collected 82 cases of IMN and secondary MN (lupus-related (SLEMN) and non-SLEMN) from 4 Institutions. Formalin fixed paraffin embedded sections were stained for PLA2R and scored blindly as positive or negative and results were correlated with clinical, histomorphologic, IF and electron microscopy (EM) findings.

Results

Of 37 IMN, PLA2R-positivity was observed in 62% of cases, was variable in non-SLEMN (54%) and mostly negative in SLEMN (91%). Thus, PLA2R staining alone was not sufficient to parse IMN from non-SLEMN (p=0.61). SLEMN were more likely to show mesangial expansion compared to IMN and non-SLEMN (p<0.0001 and p=0.0016 respectively), subendothelial deposits (p<0.0001) and more mesangial deposits compared to IMN (p=0.0004) but not non-SLEMN (p=0.1228). Tubuloreticular inclusions were more frequent in SLEMN and non-SLEMN compared to IMN (p<0.0001 and 0.0004 respectively) with no difference between SLEMN and non-SLEMN. IF patterns were similar in IMN and non-SLEMN with more “full-house” patterns in SLEMN. PLA2R-negative cases were more likely to have mesangial expansion, full house staining, subendothelial and mesangial deposits (p=0.0381, 0.0341, 0.0008 and 0.0351 respectively). Glomerular basement membrane alterations, global/segmental glomerulosclerosis (%) and tubulointerstitial scarring (%) did not differ significantly between groups.

Conclusion

We show a higher prevalence (62%) of PLA2R positive IMN compared to previous reports. However, PLA2R positivity was observed in a 54% of secondary MN (non-SLEMN). PLA2R-positivity did not correlate with any specific histological characteristics but was uncommon in SLEMN.