Membranous-Like Glomerulopathy with Masked IgG Kappa Deposits: A Case Series

Introduction: Membranous-like glomerulopathy with masked IgG kappa deposits (MGMID) is a rare, underrecognized cause of CKD, characterized by glomerular immune deposits only visible after protease digestion. Management is challenging due to the lack of proven therapies. Here we present a case series of patients with MGMID. Case Description: Three female patients, aged 17, 23, and 51, were diagnosed with MGMID. Two identified as White and one as Hispanic. At diagnosis, eGFR ranged from 12 to 117 mL/min/1.73m2, and UPCR ranged from 1.2 to 7.0. All had normal serum protein electrophoresis and no clonal bone marrow abnormalities. Renal biopsies showed masked IgG kappa deposits with variable chronicity, including global and segmental glomerulosclerosis. Treatments included rituximab, rituximab plus mycophenolate and steroids, and CyBorD therapy. After a median follow-up of 26 months, two patients had stable or improved renal function, avoiding ESRD. However, one patient rapidly progressed to ESRD within 8 months. Discussion: This case series highlights the clinical variability of MGMID, which can affect patients across a wide age spectrum and lead to diverse outcomes underscoring the urgent need for further research to guide treatment and improve prognosis.