M-type phospholipase A2 receptor (PLA2R) glomerular staining in pediatric idiopathic membranous nephropathy

Identifying M-type phospholipase A(2) receptor (PLA(2)R) is a landmark breakthrough for understanding adult idiopathic membranous nephropathy (iMN). However, potential roles for PLA(2)R in pediatric iMN have not been well investigated. A total of 34 pediatric iMN patients who underwent kidney biopsy between 1972 and 2015 were enrolled in this study. The study cohort consisted of 15 children aged from 3 to 9 years and 19 aged from 10 to 15 years. In all cases, secondary causes of MN, including infections, autoimmune diseases, and others, were ruled out. We examined PLA(2)R glomerular staining in stored, formalin-fixed, paraffin-embedded kidney biopsy samples. Kidney biopsy specimens obtained from an adult patient with iMN and an adult patient with lupus-associated MN were also examined to assess our PLA(2)R staining procedure. Granular staining of PLA(2)R along glomerular capillary loops was present in two patients: an 11-year-old girl and 12-year-old boy identified during a school urine screening test and who presented with mild proteinuria at the time of biopsy. Interestingly, the intensity of PLA(2)R glomerular staining in these patients was weaker than that of a PLA(2)R-positive adult iMN patient. There were no PLA(2)R-positive patients among our cohort of children younger than 10 years. This preliminary study suggests PLA(2)R may play a role in some adolescent and preteen iMN patients but may be less frequently associated with iMN during childhood.