A case report of immunoglobulin M nephropathy manifesting as crescentic glomerulonephritis and nephrotic syndrome in an adult

BACKGROUND: The nature of immunoglobulin M (IgM) nephropathy has been controversial for a long time, but it is now considered an independent disease like immunoglobulin A nephropathy. IgM nephropathy has been known to have various clinical manifestations ranging from asymptomatic hematuria and/or proteinuria to nephrotic syndrome. Recently, one case of IgM nephropathy manifesting as crescentic glomerulonephritis (GN) was reported in a child. CASE PRESENTATION: We experienced a case of IgM nephropathy that manifested clinically as nephritic and nephrotic syndrome with pathologically confirmed crescentic GN in a 30-year-old woman. We administered a calcineurin inhibitor and corticosteroids to treat the ongoing nephrotic syndrome after remission of crescentic GN. As a result, her proteinuria was significantly reduced and edema improved. CONCLUSIONS: We described a case of IgM nephropathy in an adult patient who initially developed crescentic GN with nephritic and nephrotic syndrome. This case report could contribute to a deeper understanding of IgM nephropathy.