A 7-year-old girl is brought to the emergency department by her grandfather for evaluation of dark urine. He reports noticing earlier today that her urine was “brown like cola.” The patient's past medical history is unremarkable except for a sore throat three weeks prior that was treated with amoxicillin. There is no family history of hematologic disorders or renal disease. Vital signs include temperature 37.1 C (98.8 F), pulse 103 beats/minute, blood pressure 125/83 mmHg, and respirations 18/minute. On physical examination, mild periorbital edema is noted; the remainder of the exam is unremarkable.
If a renal biopsy were performed and examined under electron microscopy, which of the following findings would most likely be noted?
E) Subepithelial humps
This patient has poststreptococcal glomerulonephritis (PSGN), a nephritic syndrome that occurs after skin or pharyngeal infection with a group A beta-hemolytic streptococcal organism. It is most common in children and occurs 2-3 weeks post-infection. It classically presents with hematuria (described as cola, tea, or brown colored), oliguria, hypertension, and periorbital edema. Subepithelial humps are characteristic of PSGN and seen on electron microscopy. Effacement of the foot processes of podocytes is observed in minimal change disease and focal segmental glomerulosclerosis, and it is seen with electron microscopy. Hypercellular, inflamed glomeruli are observed in PSGN but seen on hematoxylin and eosin (H&E) staining, not electron microscopy. Mesangial immune complex deposits are seen in IgA nephropathy (Berger disease). In contrast, the deposits in PSGN are subepithelial. Normal glomeruli are seen in minimal change disease, which presents with a nephrotic picture, not nephritic like in this patient.
Key Learning Point
Poststreptococcal glomerulonephritis is a nephritic syndrome that occurs after skin or pharyngeal infection with a group A beta-hemolytic streptococcal organism, is most common in children, and occurs 2-3 weeks post-infection. It classically presents with hematuria, oliguria, hypertension, and periorbital edema. Subepithelial humps are characteristic of PSGN and seen on electron microscopy.
