A 7-year-old boy presents with bilateral swelling around his eyes. His parents state that the child's eyes have become "puffy" over the past several weeks, and his urine has become cocoa-colored. Physical examination reveals bilateral periorbital edema, but peripheral edema is not found. The boy is afebrile and his blood pressure is slightly elevated. A urinary dipstick reveals mild proteinuria, while microscopic examination of the boy's urine reveals hematuria with red blood cell casts. Laboratory tests reveal increased ASO titers and decreased serum C3 levels, but C2 and C4 levels are normal. A throat swab for streptococci is negative. A microscopic section from the kidney reveals increased numbers of cells within the glomeruli. An electron microscopic section of the kidney reveals large electron-dense deposits in the glomeruli that are located between the basement membrane and the podocytes. The foot processes of the podocytes are otherwise unremarkable. Which one of the following renal diseases most likely produced the abnormalities in this young boy?
) In a young patient who presents with signs of edema, three renal diseases are in the differential diagnosis. These diseases have similar names and findings, which makes them easily confused with each other. For example, minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), and post-streptococcal glomerulonephritis may all produce nephrotic syndrome, which is characterized by marked proteinuria. This finding can be documented by the presence of protein in a dipstick examination of the urine. Although signs of nephritic syndrome, such as hematuria, may be seen with FSGS, young children are more often found to have acute poststreptococcal glomerulonephritis. This illness typically occurs 1 to 3 weeks after a group A a-hemolytic streptococcal infection of the pharynx or skin, such as impetigo or scarlet fever. Patients develop hematuria, red cell casts,mild periorbital edema, and increased blood pressure. Laboratory tests reveal increased ASO titers and decreased C3. Cultures taken at the time of presentation with renal symptoms are negative. Light microscopy reveals diffuse endothelial and mesangial cell proliferation with neutrophil infiltration, so that narrowing of capillary lumina and enlargement of the glomerular tuft to fill the Bowman's space occur. Electron microscopy reveals the mesangial deposits and large, hump-shaped subepithelial deposits in peripheral capillary loops that are characteristic. Immunofluorescence shows granular deposits containing IgG, C3, and often fibrin in glomerular capillary walls and mesangium. Children with poststreptococcal glomerulonephritis usually recover, and therapy is suppoive only Reference: Robbins & Cotran Pathologic Basis of Disease, 9edition
Acute post-streptococcal glomerulonephritis
Focal segmental glomerulonephritis
Membranous glomerulonephritis
Minimal change disease
miscellaneous