The Question
A 28-year-old man presents to the clinic for evaluation of worsening leg swelling over the past three weeks. He has also noticed puffiness around his eyes in the morning and foamy urine. His medical history is notable for Hodgkin lymphoma, for which he was treated with chemotherapy 5 years ago and has been in complete remission. He takes no medications. On examination, his temperature is 37.0°C (98.6°F), blood pressure is 130/80 mmHg, pulse is 78/min, and respirations are 16/min. There is prominent periorbital edema and 3+ pitting edema to the mid-shins bilaterally. The remainder of the examination is unremarkable. Laboratory studies show: Serum creatinine 1.0 mg/dL; Serum albumin 2.2 g/dL; Total cholesterol 350 mg/dL. Urinalysis shows 4+ protein and is negative for blood, leukocytes, and nitrites. Microscopic examination reveals oval fat bodies. Which of the following is the most likely pathologic finding on kidney biopsy?
See the answer and explanation below:
Post-Call Recovery Reads
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View on AmazonThe Correct Answer
A
Explanation
Clinical Pearl
Minimal change disease, the classic cause of nephrotic syndrome in children, can occur in adults and is strongly associated with Hodgkin lymphoma and NSAID use. The diagnosis is confirmed by electron microscopy showing diffuse effacement of podocyte foot processes, as light microscopy and immunofluorescence are typically normal.
Explanation:
This patient presents with classic features of nephrotic syndrome: heavy proteinuria (>3.5 g/day, inferred from 4+ protein and a low serum albumin), hypoalbuminemia, edema, and hyperlipidemia (oval fat bodies in the urine are also characteristic). In an adult with a history of Hodgkin lymphoma, the most likely underlying cause is minimal change disease (MCD). The correct answer (A) describes the pathognomonic finding for MCD, which is diffuse effacement of the podocyte foot processes visible only on electron microscopy. Light microscopy in MCD is, by definition, normal. Thickened glomerular basement membranes with subepithelial 'spikes' (C) is characteristic of membranous nephropathy, which is the most common cause of primary nephrotic syndrome in white adults but is more strongly associated with solid tumors (lung, colon) than with lymphoma. Segmental sclerosis (D) describes focal segmental glomerulosclerosis (FSGS), another important cause of nephrotic syndrome that is less specifically associated with Hodgkin lymphoma. Mesangial C3 deposits (B) suggest a complement-mediated process like post-infectious glomerulonephritis, which typically presents with a more 'nephritic' picture (hematuria, hypertension, renal failure) and follows an infection. Nodular glomerulosclerosis (E) is the hallmark of diabetic nephropathy, and this patient has no history of diabetes.
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