1 Renal Research Group, Institute of Medicine and 2 The Gade Institute, Department of Pathology, University of Bergen, Bergen, Norway
Correspondence and offprint requests to: Einar Svarstad, Renal Research Group, Medical Dept, N-5021 Haukeland University Hospital, Norway. Email: einar.svarstad{at}helse-bergen.no
Keywords: Fabry's disease; renal biopsy; stereomicroscopy
Case
A 43-year-old female Fabry patient presented with asymptomatic slight albuminuria (0.043 g/l), normal glomerular filtration rate (120 ml/min/1.73 m2) and normal echocardiography. In younger age she had complained of typical burning pains in her extremities. A renal biopsy was done in the routine work-up, according to our Fabry protocol. The biopsy findings (16 G needle) are shown in Figures 1A and 1B. Figure 1A demonstrates the white-coloured superficial glomeruli seen in the stereomicroscope immediately after the biopsy procedure. The biopsy specimen is examined with 1040x magnification in a drop of formaldehyde and illuminated by sharp, concentrated light from above. Subsequent light microscopy (Figure 1B) showed typical podocyte accumulation of glycosphingolipids in the same patient (McDowell's fixative).
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We have noticed that the visible glomeruli in biopsies from both hemizygous and heterozygous Fabry patients appear with a striking white colour in stereomicroscopy. The white colour is probably caused by the lipid content of the glycosphingolipid deposits in the podocytes. This colour is markedly different from the usual reddish-coloured glomeruli seen in patients with normal kidneys and all other types of renal disease we have seen, as demonstrated by the bedside stereomicroscopic findings in a patient with IgA nephritis, normal podocytes, patchy tubulointerstitial scarring and slightly elevated serum creatinine (Figure 1C).
The clinical diagnosis of Fabry's disease may be difficult in non-classic phenotypes and when a family history is lacking [13] and the diagnosis may be missed in inexperienced hands if only routine light microscopy is done. In our department, renal biopsy specimens are subject to routine stereomicroscopy by an experienced clinician. We conclude that an incidental finding of white glomeruli in the bedside stereomicroscopic examination of a renal biopsy should raise the suspicion and present an immediate clue to the Fabry diagnosis. A second biopsy specimen fixed in glutaraldehyde (McDowell's fixative) for light microscopy and electron microscopy will secure the morphological diagnosis of Fabry's disease.
Conflict of interest statement. None declared.
References