IMAGE QUIZ

A 62 year old patient on chronic dialysis develops lower extremity ulceration (Fig. 1). Skin biopsy is shown (Fig.2). What is the most likely diagnosis?

Fig.1

Fig.2

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Answer to Image Quiz of 11/15/11 is thin-basement abnormality (TBMA)

This is an electron micrograph (above) of a glomerulus of a 35-year old patient with hematuria on urine dipstick. The rest of the urinalysis is normal. Renal function is normal. What is the diagnosis?

Explanation

Thin basement abnormality (TBMA) is a relatively common familial disorder, occurring in 7% of the renal biopsies [1] and up to 10% of general population [2]. Tiebosch et al suggested that the diagnosis of TBMA should be based on the demonstration of an average GBM width to be less than 264 nm based on multiple measurements by the orthogonal intercept method.[3]. The EM reveals uniform thinning of the glomerular basement membrane from the normal of ≈300 to 400 nanometers (nm) to ≈150 to 250 nm. There is a nice review by Tryggvason et al here.

References

1. Dische FE, Anderson VE, Keane SJ, et al.Incidence of thin membrane nephropathy: morphometric investigation of a population sample. J Clin Pathol 1990; 43:457-460.

2. Aarons I, Smith PS, Davies RA, et al.Thin membrane nephropathy: a clinico-pathological study. Clin Nephrol 1989; 32:151-158.

3. Tiebosch AT, Frederik PM, van Breda Vriesman PJ, et al.Thin-basement-membrane nephropathy in adults with persistent hematuria. N Engl J Med 1989; 320:14-18.