This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
A 4 year-old boy, develops a large erythematous rash around the site of a mosquito bite. One month later, he is taken to a pediatrician because of a puffy face and swollen ankles. The scanty urine sample has a reddish-brown hue, and contains both red blood cells and protein. Which of the following distinctive features would be most likely to be seen on renal biopsy? 
Select and explain. 
A. Fusion of podocyte foot processes, B. IgA in the mesangium, C. Linear IgG deposits, D. Subepithelial electron dense humps
D: Subepithelial electron dense humps
Answer: D: Subepithelial electron dense humps 
Explanation: The disease is poststreptococcal glomerulonephritis, which can follow either streptococcal pharyngitis (one to two weeks after the infection) or skin infection (three to six weeks after the infection). The child is showing signs of both nephritis (hematuria) and nephrosis (puffy face and swollen ankles). The characteristic feature of this disease on renal biopsy is the presence of subepithelial humps, visible either by light or electron microscopy. Fusion of podocyte foot processes suggests minimal change disease. IgA in the mesangium suggests Berger's disease. Linear IgG deposits suggests anti-glomerular basement membrane disease, which is called Goodpasture's disease if it is accompanied by pulmonary damage. Onion-skinning of renal aerioles suggests malignant hypeension.