A 17-year-old boy is brought to the office due to occasional blood in the urine. The first episode occurred 1 year ago during a flulike illness, and resolved spontaneously. The patient had a similar episode about 6 months ago, which also seemed to resolve. He has no other medical conditions and does not use tobacco or alcohol. There is no history of blood or kidney disorders in the family. Vital signs are normal. On laboratory evaluation, blood urea nitrogen level is 14 mg/dL and creatinine is 0.8 mg/dL. Urinalysis results are as follows: A renal biopsy is performed. Which of the following findings is most likely to be seen on microscopic evaluation?

Question

A 17-year-old boy is brought to the office due to occasional blood in the urine.  The first episode occurred 1 year ago during a flulike illness, and resolved spontaneously.  The patient had a similar episode about 6 months ago, which also seemed to resolve.  He has no other medical conditions and does not use tobacco or alcohol.  There is no history of blood or kidney disorders in the family.  Vital signs are normal.  On laboratory evaluation, blood urea nitrogen level is 14 mg/dL and creatinine is 0.8 mg/dL.  Urinalysis results are as follows:  A renal biopsy is performed.  Which of the following findings is most likely to be seen on microscopic evaluation?

Quizplus · Accepted Answer

11ec160b_3a33_fee7_9249_8dc99d23e574_MD0001_00 This patient likely has IgA nephropathy (Berger disease), the most common cause of glomerulonephritis. It typically affects older children and young adults and presents with painless hematuria that is often accompanied by an upper respiratory tract infection. The hematuria lasts for several days and then subsides temporarily, returning every few months or with another upper respiratory infection (synpharyngitic hematuria). Complement levels are usually normal. Renal biopsy will show mesangial hypercellularity with mesangial IgA deposits seen by immunofluorescence. When IgA nephropathy is accompanied by extrarenal symptoms (eg, abdominal pain, arthralgias, purpuric skin lesions), the syndrome is called Henoch-Schönlein purpura. (Choice A) The kidney is often affected by amyloidosis. On Congo red staining, amyloid deposits appear red-pink under light microscopy and have an apple-green birefringence under polarized light. Amyloidosis typically presents in older adults as nephrotic syndrome with significant edema and proteinuria. (Choice B) Crescent formation with linear IgG deposits occurs in patients with anti-glomerular basement membrane antibody disease (Goodpasture disease). This condition generally presents as rapidly progressive glomerulonephritis associated with an acute rise in creatinine and decreased urine output; patients also often have hemoptysis. The disease is rare in children. (Choice C) Minimal change disease (MCD) is characterized by effacement of podocyte foot processes on electron microscopy. MCD typically results in nephrotic syndrome with generalized edema and high levels of proteinuria; recurrent hematuria associated with an upper respiratory infection is more consistent with IgA nephropathy. (Choice D) Poststreptococcal glomerulonephritis (PSGN) demonstrates granular IgG and C3 deposits along the glomerular basement membrane. However, hematuria in PSGN usually develops 1-3 weeks after streptococcal pharyngitis (postpharyngitic nephritis), and reoccurrence is rare. (Choice E) Alport syndrome is a disorder of type IV collagen that causes a nephritic syndrome; however, it is associated with hearing loss and ocular abnormalities. Electron microscopy shows a lamellated basement membrane with irregular thinning and thickening ("basket-weave" appearance). (Choice G) Focal segmental glomerular sclerosis typically causes nephrotic syndrome. Recurrent episodes of macroscopic hematuria are unexpected. (Choice H) Thin basement membrane disease is an autosomal dominant disorder that results in a thin basement membrane with recurrent microscopic hematuria, gross hematuria, or flank pain. Due to the inheritance pattern, patients typically have a family history of hematuria. Educational objective: IgA nephropathy (Berger disease) frequently presents as recurrent, self-limited, painless hematuria; episodes often occur concurrently with an upper respiratory tract infection. Kidney biopsy will show mesangial IgA deposits on immunofluorescence. In contrast, poststreptococcal glomerulonephritis is seen 1-3 weeks after streptococcal pharyngitis and is usually not recurrent.

A 17-Year-Old Boy Is Brought to the Office Due to Occasional