A new phenotype of monoclonal gammopathy of renal significance
By:
[1] Mignano SE, Pascal V, Odioemene NE, Forehand W, Javaugue V, Said SM, Sethi S, Sirac C, Nasr SH: Monoclonal Immunoglobulin Crystalline Membranous Nephropathy. Am J Kidney Dis 2024, 84:120-5. https://doi.org/10.1053/j.ajkd.2023.11.011
[2] Nasr SH, Sirac C, Leung N, Bridoux F: Monoclonal immunoglobulin crystalline nephropathies. Kidney Int 2024. https://doi.org/10.1016/j.kint.2024.02.027
Blogged by Nicolas Kozakowski, January 6th, 2025
The manifold of histological presentations of MGRS has been recently expanded with the case report by Mignano et al., describing a monoclonal immunoglobulin crystalline membranous
nephropathy (MN)1. The fact that both monoclonal immunoglobulin-induced MN (alone or in association with other lesions) and crystalline variants of MGRS are rare events renders the association of these presentations quite exciting. The subepithelial electron-dense deposits reported in monoclonal MN cases are usually comparable to those of non-monoclonal MNs, however, this particular case displayed electron-dense rhomboid to needle-shaped crystals. Interestingly, the authors completed their analysis with an immunoglobulin repertoire sequencing assay, providing insights in the physicochemical properties of the pathogenic immunoglobulin and potential explanations on its crystallization.
Worth mentioning, some of the same authors provided an overview of monoclonal immunoglobulin crystalline nephropathies in a mini review shortly after, including this new phenotype2.