The Exostosin Immunohistochemical Status Differentiates Lupus Membranous Nephropathy Subsets With Different Outcomes

Exostosin (EXT) 1 and EXT2 proteins are recently discovered major components of the subepithelial deposits in a subset of patients with membranous nephropathy (MN).1,2 Although the detection of EXT1/2 seems to be a distinctive feature of MN related to systemic lupus erythematosus (SLE),1 the exact frequency of EXT-positive, SLE-associated MN (SLE-MN) and its potential clinical significance are not well determined.Here, we retrospectively evaluated 86 consecutive patients with biopsy-proven pure class 5 SLE-MN diagnosed between January 2010 and December 2018 in 2 nephropathology centers (La Pitié Salpêtrière and Tenon hospitals) in Paris, France; mixed classes (3 + 5 and 4 + 5 of the 2003 ISN/Renal Pathology Society classification)3 were excluded.