In a case of minimal change disease, which microscopy finding is expected?

In minimal change disease, the expected microscopy finding is the fusion of epithelial foot processes. This condition typically affects children and is characterized by nephrotic syndrome, where patients present with edema, proteinuria, and hypoalbuminemia.

The pathophysiology of minimal change disease is not completely understood, but it's believed to be related to immune dysregulation, leading to alterations in the glomerular filtration barrier. Under light microscopy, the glomeruli can appear normal, which is a hallmark of this disease. However, under electron microscopy, the notable feature is the effacement or fusion of the podocyte foot processes. This results in a disruption of the filtration barrier, allowing large amounts of protein to leak into the urine, hence the term "minimal change," as no significant changes are visible on standard histological staining.

Other choices discuss changes typically seen in other types of glomerular diseases. For instance, thickening of the glomerular basement membrane is more commonly seen in diabetic nephropathy or other forms of nephron damage. Immune complex depositions in mesangial areas are characteristic of diseases like lupus nephritis or IgA nephropathy, which involve significant inflammation and immune response. Increased mesangial cellularity may