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IgM Nephropathy (IgMN) is a rare entity of unknown incidence in the world and in our country. In this study, we present a case series that illustrates the clinical characteristics and response to treatment of this disease. Our aim is to provide an overview of IgMN in Western Mexico.
Retrospective study of kidney biopsies performed between January 2017 and December 2022. Patients with a diagnosis of IgMN, defined as deposit of IgM in the mesangium by IF study, without deposits of other type of immunoglobulins. A retrospective electronic file review was performed.
Of a total of 692 patients in the glomerular diseases registry during the 2017-2022 period, 11 cases of IgMN were found; 1 case was excluded due to lack of information in the electronic record (Table 1). 9/10 patients were men. The median age at presentation was 4 years. 9/10 cases presented as steroid-resistant nephrotic syndrome and 1 as hematuria/proteinuria syndrome. 8/10 patients had preserved normal renal function at the time of diagnosis. Initial treatment was steroids in 8/10 and steroids with cyclophosphamide in 2/10. All had a partial response with the initial treatment.
Two patients lost follow-up. Of the rest, 7/8 were treated with cyclosporine + steroids, obtaining a complete response in 5/7. One patient had a complete response with rituximab + plasmapheresis, and another patient had a complete response with rituximab. Only one patient was maintained on low-dose steroids, showing a partial response.
IgMN remains a rare entity. Most patients with IgMN presented as steroid-resistant nephrotic syndrome. Initial treatment with steroids or steroids/cyclophosphamide achieved partial responses in most cases. Most patients had a complete response with either cyclosporine or rituximab.