A 4-year-old girl presents with swelling of the legs and ankles. Physical examination reveals pitting edema of the lower extremities. Urinalysis show 2+ proteinuria. The urinary sediment contains no inflammatory cells or red blood cells. Serum levels of BUN and creatinine are normal. The patient recovers completely after a course of corticosteroids. For the patient, electron microscopy of a renal biopsy specimen prior to treatment would most likely demonstrate which of the following abnormalities?

The light microscopic appearance of glomeruli in minimal change glomerulopathy is essentially normal. However, electron microscopic examination of glomeruli reveals total effacement of visceral epithelial cell foot processes. This retraction presumably results from extensive cell swelling and occurs in virtually all cases of proteinuria in the nephrotic range. It is not a specific marker, but is characteristic of minimal change glomerulopathy Minimal change disease is not characterized by deposits of immune complexes (choices B and C) and does not reflect changes in the basement membrane (choice A). Choice E is incorrect because minimal change disease involves changes in glomeruli, not renal tubules.Diagnosis: Minimal change nephrotic syndrome