The pathological features of acute nephritis include enlarged kidneys, and under the light microscope, there is diffuse proliferation of glomeruli, capillary endothelial cells, and mesangial cells. During the acute phase, there can be infiltration of neutrophils and mononuclear cells. In severe cases, constriction or occlusion of the capillary loops occurs, and the renal interstitium has edema and infiltration of inflammatory cells. Under immunofluorescence, there are deposits of IgG and C3 appearing as granular deposits along the glomerular capillary walls and mesangial areas. Under electron microscopy, there are hump-shaped electron-dense deposits beneath the glomerular epithelium. Acute nephritis is commonly seen in children, characterized by a sudden onset and symptoms such as hematuria, increased urinary protein, edema, and elevated blood pressure, even transient renal function decline may occur.