CASE 181 (March 2021)
An 76-year-old man with a past medical history of hypertension and chronic obstructive pulmonary disease (COPD) presented to the emergency department with malaise of about 5 days duration. He also experienced fatigue, lower extremity pain, shortness of breath, and cough. No diarrhea, weight loss, history of malignancy, or kidney disease were reported. About a week prior to the onset of symptoms he had taken ibuprofen four times a day for 5 days due to back pain.
His vital signs were normal, and his physical examination was unremarkable. Urinalysis showed microscopic hematuria and proteinuria: 1.2 g/24h. Serum creatinina: 2,4 mg/dL, BUN: 38,2 mg/dL. Serum complement (C3, C4) was normal. Antinuclear-antibody, anti-dsDNA, and ANCA were negative. Liver function tests: normal.
A kidney biopsy was carried out. See the images.
Figure 1. Masson's trichrome stain, X100.
Figure 2. H&E, X200.
Figure 3. H&E, X400. Normal glomeruli.
Figure 4. PAS, X400.
Figure 5. Methenamine-silver stain, X400.
Figure 6. H&E, X400.
Figure 7. H&E, X400.
Figure 8. Methenamine-silver stain, X100.
Figure 9. H&E, X400.
Figure 10. H&E, X400. Liquefactive necrosis. This necrosis is located in the medullary papilla.
Figure 11. PAS, X200.
Figure 12. Masson's trichrome stain, X100.
Figure 13. Masson's trichrome stain, X200.
Figure 14. PAS, X400.
Direct immunofluorescence for IgA, IgG, IgM, C3, C1q, kappa, and lambda: Negative.
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