A 72-year-old woman is brought to the office by her daughter for evaluation of leg swelling and fatigue. The patient recently moved in with her daughter and has not seen a physician in several years. She has had bilateral lower extremity swelling for the past 3 months. The patient has had fatigue and joint pains for the past several years, which she attributes to old age. The daughter states that the patient seems tired all the time, barely eats anything, and "is just not herself." The patient takes no medication and does not use tobacco, alcohol, or illicit drugs. Blood pressure is 116/72 mm Hg and pulse is 78/min and regular. The lungs are clear on auscultation and heart sounds are normal. The abdomen is soft and nontender. Examination of the lower extremities reveals 3+ pitting edema. There are scattered ecchymoses, and hand examination findings are shown in the exhibit. Laboratory results are as follows: Urinalysis reveals 4+ protein with no cells or casts. A renal biopsy of this patient is most likely to show which of the following findings?

Question

A 72-year-old woman is brought to the office by her daughter for evaluation of leg swelling and fatigue.  The patient recently moved in with her daughter and has not seen a physician in several years.  She has had bilateral lower extremity swelling for the past 3 months.  The patient has had fatigue and joint pains for the past several years, which she attributes to old age.  The daughter states that the patient seems tired all the time, barely eats anything, and "is just not herself."  The patient takes no medication and does not use tobacco, alcohol, or illicit drugs.  Blood pressure is 116/72 mm Hg and pulse is 78/min and regular.  The lungs are clear on auscultation and heart sounds are normal.  The abdomen is soft and nontender.  Examination of the lower extremities reveals 3+ pitting edema.  There are scattered ecchymoses, and hand examination findings are shown in the exhibit.  Laboratory results are as follows:  Urinalysis reveals 4+ protein with no cells or casts.  A renal biopsy of this patient is most likely to show which of the following findings?

Quizplus · Accepted Answer

This patient has nephrotic syndrome (ie, proteinuria, pitting edema, hypoalbuminemia). In association with joint pains and hand deformities (eg, ulnar deviation, swan neck deformity, nodules), this presentation suggests rheumatoid arthritis (RA) complicated by AA amyloidosis. Serum amyloid A protein is an acute phase reactant; therefore, AA amyloidosis often develops in the setting of chronic inflammation (eg, osteomyelitis, rheumatologic disease). Long-standing RA is the most common cause, and patients with untreated disease are particularly susceptible. The most common manifestation is renal disease with proteinuria or nephrotic syndrome. Skin involvement can lead to thickening or easy bruising (eg, ecchymoses). Cardiac (eg, cardiomyopathy), gastrointestinal (eg, hepatomegaly, dysmotility), and neurologic (eg, peripheral neuropathy, dementia, stroke) disease may also occur. Laboratory studies can show elevated inflammatory markers (eg, erythrocyte sedimentation rate) and normocytic anemia (due to chronic inflammation). The diagnosis is confirmed with the presence of amyloid on tissue biopsy (eg, fat pad). Renal biopsy can be considered if fat pad biopsy is nondiagnostic. Histology demonstrates amorphous hyaline material that stains with Congo red; green birefringence is noted under polarized light. (Choice B) Proliferative glomerulonephritis demonstrates cellular proliferation and glomerular immune deposits on histology but usually presents with hypertension, hematuria, and red blood cell casts. In addition, it is typically associated with systemic lupus erythematosus (SLE), not RA. (Choice C) Hypertensive nephrosclerosis is characterized by hyalinization of the arterioles and small arteries and results in chronic kidney disease; however, it is caused by long-standing, uncontrolled hypertension (this patient's blood pressure is normal). In addition, nephrotic-range proteinuria is unexpected. (Choice D) Acute interstitial nephritis causes renal injury and is classically associated with certain drugs. It can occur with systemic disease (eg, SLE) but is less commonly associated with RA. It is typically characterized by fevers, rash, and urinary white blood cells and white blood cell casts. (Choice E) Hyperuricemia can result in urate deposition within the renal interstitium and can lead to renal injury, and gout can cause joint pain and deformity. However, urate crystals are expected on urinalysis, and gout flares typically cause a monoarticular arthritis characterized by a warm, swollen, exquisitely painful joint. Educational objective: AA amyloidosis occurs in the setting of chronic inflammation and is most commonly seen in patients with long-standing rheumatoid arthritis. The most common manifestation is renal disease characterized by proteinuria and nephrotic syndrome; cardiac and gastrointestinal disease may also occur. The diagnosis is confirmed with biopsy demonstrating amorphous hyaline material that stains with Congo red.

A 72-Year-Old Woman Is Brought to the Office by Her