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A 40-year old man consults a physician because of reddish discoloration of his urine. Laboratory examination of the urine demonstrates red cells, red cell casts, and proteinuria. Blood studies demonstrate serum creatinine levels of twice the upper limit of normal. One week later, the patient is seen in the emergency department because he is coughing up large quantities of fresh blood. The decision is made to perform a renal biopsy. The initial hematoxylin and eosin stained slides show a proliferative, rapidly progressive glomerulonephritis. Which of the following additional findings on special studies would most likely lead to the correct diagnosis?
Options:
A. Electron dense subepithelial humps
B. Linear deposits of IgG
C. Mesangial IgA deposits
D. Podocyte foot process fusion
E. Sickled cells in vasa recta
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Yes B it is.
This is Goodpasture syndrome, in which autoantibodies (usually IgG) are directed against the basement membranes found in the renal glomeruli and pulmonary alveoli, predisposing for both rapidly progressive glomerulonephritis and pulmonary hemorrhage. These antibodies can be detected with fluorescent techniques as linear deposits following the basement membranes in both renal and pulmonary biopsies. Goodpasture syndrome formerly had a dismal prognosis, with deaths related to either renal failure or pulmonary hemorrhage, but the prognosis has improved with intensive use of plasma exchange.
Associate electron dense subepithelial humps (choice A) with poststreptococcal glomerulonephritis, which can produce rapidly progressive glomerulonephritis, but does not produce lung disease.
Associate mesangial IgA deposits (choice C) with Berger disease, which damages the kidney, but not the lung.
Associate podocyte foot process fusion (choice D) with minimal change disease (lipoid nephrosis). This condition does not produce striking glomerular changes on routine sections and does not damage the lung.
Associate sickled cells in vasa recta (choice E) with sickle cell anemia, which does not cause lung hemorrhage.
