I. What is Minimal Change Disease?
Minimal Change Disease (MCD), also called Lipoid Nephrosis or Minimal Change Glomerulonephritis, is one of the pathological types of Nephrotic Syndrome (NS). Characterized by unobvious or mild glomerular changes under light microscope, it gains this name. From pathological aspects, there is usually large amount of lipidoses in renal tubular epithelial cells in this disease, so it is also named Lipoid Nephrosis. This disease is the most common type of NS and it is often seen in teenagers and children while adult patients are less. 65%~85% of childhood NS is caused by MCD, so it is the most common cause of childhood NS.
II. Pathological changes of Minimal Change Disease
MCD is different from other types of Nephritis. There is no deposit by electron microscopic observation and no immunoglobulins or receptors are found in the glomeruli by immunofluorescence. The causes and pathogenesis are still unclear. In some cases, patients may have this disease after respiratory tract infection or there may be co-occur of other hypersensitivity diseases like allergic rhinitis and eczema, prompting a possibility of its relation to immunologic mechanism. Incidence rate of MCD is higher in patients with Hodgkin Disease, who usually have T-cells functional defect. So it is considered that onset of MCD is possibly related to abnormal function of T-cells. Some scholars point out that decrease of glomerular polyanion may be the reason why this disease has glomerular capillary epithelial cells changes and large amount of proteinuria.
There is no obvious change of the Glomeruli or only mild segmental mesangial proliferation can be seen under the light microscope. Under electron microscope, there is diffuse disappearance of foot process of the epithelial cells on glomerular visceral layer; increased Golgi’s apparatus and endoplasmic reticulum in the cells and lipid droplet can also be seen. There are often microvilli formed on the surface of the cells. Disappearance of foot process is not only seen in Lipoid Nephrosis, but also in massive proteinuria and Nephrotic Syndrome caused by other factors. Changes of the epithelial cells can recover to a normal state after treatment or remission of proteinuria.
There are many hyaloid droplets and lipoid deposition in renal tubular epithelial cells. The glomerualr capillary permeability strengthened, large amount of lipoprotein is filtered out and reabsorbed by the renal tubules. There can be hyaline cast in renal tubules. These changes are usually at equal pace with proteinuria.
Gross appearance includes renal swelling, enlarged volume and pale color. Because of large amount of lipoid deposition, yellow stripes can be seen on the cross section of the kidneys.
III. Clinical symptoms of Minimal Change Disease
Patients with Minimal Change Disease often have manifestations of Nephrotic Syndrome, like massive proteinuria and severe swelling. Some patients may show typical “three highs and one…