The answers
a.) What is the differential diagnosis
This patient likely has acute glomerulonephritis, even though we have incomplete clinical information (for example, no urine microscopy). The likeliest etiology is post-infectious glomerulonephritis, albeit other possibilities include an ANCA associated small vessel vasculitis (prior history of pulmonary nodules), and IgA nephrpathy (activated by a respiratory infection), and acute interstitial nephritis (AIN)from the antibiotic used to treat the patient is also possible although the presentation doesn't fit for an AIN.
b.) what is the biopsy likely to show?
An acute glomerulonephritis, likely with crescents, and immune complex deposition on IF with immune deposits IM both sub-epitheial and intramembranous.
The case
a.) What is the differential diagnosis
This patient likely has acute glomerulonephritis, even though we have incomplete clinical information (for example, no urine microscopy). The likeliest etiology is post-infectious glomerulonephritis, albeit other possibilities include an ANCA associated small vessel vasculitis (prior history of pulmonary nodules), and IgA nephrpathy (activated by a respiratory infection), and acute interstitial nephritis (AIN)from the antibiotic used to treat the patient is also possible although the presentation doesn't fit for an AIN.
b.) what is the biopsy likely to show?
An acute glomerulonephritis, likely with crescents, and immune complex deposition on IF with immune deposits IM both sub-epitheial and intramembranous.
The case
An 82 year old female with a recent history of being diagnosed with pneumonia presents to the emergency department with generalized weakness and fatigue. She says that her urine has been lately dark-colored in the morning. She is found to have hematuria and proteinuria. Her past medical history is notable for recent pneumonia, asthma, chronic bronchitis, hypertension, history of supraventricular tachycardia, pulmonary nodules, hypercholesterolemia. Medications include Flovent 110 mcg 2 puffs twice daily, albuterol as needed, metoprolol tartrate 5 mg one daily, amlodipine 5 mg one daily, furosemide 10 mg one daily, Allegra 60 mg one daily, aspirin 81 mg one daily. Family history: no renal disease. Social history: remote tobacco abuse (quit 50 years ago), no alcohol or illicit drug use. Review of systems is unremarkable. Examination is notable for a BP of 164/84 mmHg, heart rate 70 beats/minute, respirations 20/minute, temperature 98.2, O2 saturation 99% on room air, but is otherwise negative. Laboratory data shows: WBC 6.9, HCT 34.7%, Hb 11.9 g/dL, Platelets 207 thousands, Na 140 mEq/L, K 4.8 mEq/L, Gluc 92 g/dL, BUN 15, Cr 0.55 mg/dL. Urinalysis shows: color -dark yellow, leukocyte esterase trace, nitrate negative, protein 3+, blood 3+, WBC 10-15, RBC 60-70, bacteria 2+. A renal biopsy is performed.
What is the differential diagnosis and what is the biopsy likely to show?
The renal biopsy results are as follows:
