ORIGINAL ARTICLE Rethinking peritubular capillary basement membrane multilayering in renal transplant pathology: a case report Diana Maria Lopategui 1,2 & Evelyne Lerut 3 & Maarten Naesens 4,5 & Rita Van Damme-Lombaerts 2 & Elena Levtchenko 2 & Noël Knops 2 Received: 23 July 2016 /Revised: 26 September 2016 /Accepted: 11 October 2016 # IPNA 2016 Abstract Background Severe multilayering (ML) of the peritubular capillary basement membranes in kidney allografts is consid- ered to be an ultrastructural hallmark of chronic antibody- mediated rejection (CAMR). We describe here the unexpected findings in a young male adolescent with underlying focal segmental glomerulosclerosis who underwent a living- related donor transplant procedure, a case which brought into question the specificity of ML. Methods The patient received a kidney from his mother, whose donor screening was unremarkable. He developed nephrotic-range proteinuria shortly after the procedure. Biopsies performed within the first 6 months after transplan- tation demonstrated ML (5–6 layers). Results Since there were no other criteria for CAMR, electron microscopic analysis of the baseline biopsy was performed, which in retrospect also demonstrated ML. The donor is still asymptomatic after 7 years of follow-up, with normal renal function and no proteinuria. Conclusions We discuss the phenomenon of ML in renal dis- ease and together with the findings in our case would like to draw attention to the fact that ML in the setting of renal trans- plantation is not specific to CAMR, as it can exist in several kidney diseases and even in asymptomatic donors. Keywords Transplant . Focal segmental glomerulosclerosis . Multilayering . Rejection Introduction Chronic active antibody-mediated rejection (CAMR) is an im- portant complication of renal transplantation and deemed re- sponsible for approximately 63 % of late allograft failures [1]. However, diagnosing CAMR is not straightforward, and has been under scrutiny since the recognition of its effect on long- term graft survival. The most recent revision of the diagnostic criteria for CAMR from the Banff working group requires the presence of three features: serological evidence of donor- specific antibodies, proof of antibody–vascular endothelium interaction (defined as positivity for complement degradation product C4d, microvascular injury or gene transcription alter- ations indicative of endothelial injury) and morphological signs of chronic tissue injury. Histological features considered to be indicative of chronic tissue injury include transplant glo- merulopathy based on light or electronic microscopy analysis, new onset of arterial intimal thickening or severe peritubular capillary basement membrane multilayering (ML) [2]. ML was first reported in 1973 by Zollinger et al. [3]. Studying renal allograft biopsies with histological features of transplant glomerulopathy by electron microscopy, these au- thors described splitting and reduplication of the vascular basement membrane [4]. Later studies reported ML in 90 % of allografts with transplant glomerulopathy [5] and linked it to the progression of chronic rejection [6]. As a consequence, ML was proposed as an early diagnostic marker of CAMR in * Diana Maria Lopategui dlopategui@gmail.com 1 University of Barcelona, Barcelona, Spain 2 Department of Pediatric Nephrology and Solid Organ Transplantation, University Hospitals Leuven, Leuven, Belgium 3 Department of Morphology and Molecular Pathology, University Hospitals Leuven, Leuven, Belgium 4 Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium 5 Department of Nephrology, University Hospitals Leuven, Leuven, Belgium Pediatr Nephrol DOI 10.1007/s00467-016-3541-z