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Minimal change variants: Mesangial proliferation; IgM nephropathy; C1q nephropathy

Alain Meyrier, MD
Gerald B Appel, MD
Section Editors
Richard J Glassock, MD, MACP
Fernando C Fervenza, MD, PhD
Deputy Editor
Albert Q Lam, MD


In addition to minimal change disease (MCD), three other disorders usually present with the nephrotic syndrome and may also show only minor changes on light microscopy: idiopathic mesangial proliferative glomerulonephritis; immunoglobulin M (IgM) nephropathy; and C1q nephropathy. These disorders may represent variants of MCD or focal segmental glomerulosclerosis (FSGS), but some clinicians and pathologists believe that they are separate conditions.

The nosology of IgM and C1q nephropathy is particularly unsettled. However, clinicopathologic findings suggest forms of idiopathic nephrotic syndrome that, in terms of prognosis and treatment options, are closer to FSGS than to MCD.

Idiopathic mesangial proliferative glomerulonephritis, IgM nephropathy, and C1q nephropathy will be reviewed in this topic. The pathogenesis, clinical features, diagnosis, and treatment of MCD and FSGS are discussed separately. (See "Etiology, clinical features, and diagnosis of minimal change disease in adults" and "Treatment of minimal change disease in adults" and "Epidemiology, classification, and pathogenesis of focal segmental glomerulosclerosis" and "Treatment of primary focal segmental glomerulosclerosis".)


Focal (involving less than 50 percent of glomeruli on light microscopy) or diffuse mesangial cell proliferation (involving more than 50 percent of glomeruli on light microscopy) is a relatively nonspecific response to glomerular injury. This pattern can be seen in a variety of diseases including lupus nephritis, IgA nephropathy, and mild postinfectious glomerulonephritis [1]. In addition, there is a seemingly idiopathic form in which there are either no immune deposits (in contrast to the IgA or IgG deposits in the above disorders) or focal or diffuse IgM-containing deposits in the mesangial areas. Patients with this glomerulopathy tend to present in one of two ways: with hematuria; or, more commonly, with proteinuria that is often in the nephrotic range [2,3]. Most publications dealing with the latter involve childhood idiopathic nephrotic syndrome with focal segmental glomerulosclerosis (FSGS) on renal biopsy [4].

Hematuria — Some patients with mesangial proliferative glomerulonephritis present with episodes of gross hematuria [5] or with microscopic hematuria that may be detected on a routine examination [2,3]. These findings may follow a nonstreptococcal upper respiratory infection [6], a pattern that resembles that of IgA nephropathy (see "Glomerular disease: Evaluation and differential diagnosis in adults"). The hematuria often resolves spontaneously, although persistent microscopic hematuria may be seen [2]. The renal prognosis in these patients is almost always excellent [2,7].

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Literature review current through: Nov 2017. | This topic last updated: Nov 15, 2017.
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