A 34-year-old Asian female underwent a renal biopsy as part of the workup for progressively worsening renal function (Cr = 1.6 mg/dl) and non-nephrotic proteinuria (3.1 g/g). The light microscopic findings (Fig 1) are highly suspicious for Fabry disease. The glomeruli are enlarged and show frequent visceral epithelial cells displaying abundant vacuolated/ foamy cytoplasm. Furthermore, toluidine blue stain (not shown) highlights the lipid granules within the cytoplasm of the podocytes. Interestingly, immunofluorescence (Fig 2) shows mesangial immune deposits which stain positive for IgA, kappa and lambda. The displayed electron micrograph (Fig 3) shows evidence of a dual disease. The podocytes contain numerous cytoplasmic, lamellated, lipid vacuoles (red arrow) characteristic of Fabry disease, along with frequent paramesangial electron dense deposits (green arrow) characteristic of IgA nephropathy. While both diagnoses were rendered in this case, given the clinical presentation and absence of active glomerular lesions, the IgA nephropathy, in this case, is favored to represent an incidental finding and is likely clinically insignificant. The association of these two disorders is highly unusual but has been reported in several case reports and small case series (see references).
References:
Maixnerova D, et al. The coincidence of IgA nephropathy and Fabry disease. BMC nephrol. 2013
Yang N, et al. Clinical and pathological characteristics of Fabry disease combined with IgA nephropathy in Chinese patients. Clin Nephrol. 2007; 4: 188-195.
Shimohata H, et al. Hemizygous Fabry disease associated with IgA nephropathy: a case report. J Nephrol. 2009; 22: 682-684.
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