|
|
| Membranoproliferative Glomerulonephritis Type II |
| Etiology |
•Unknown. |
| Pathogenesis |
•Membranoproliferative
glomerulonephritis type II is, in a sense, an autoimmune
disorder. •Patients have C3 nephritic factor which is an IgG
immunoglobulin directed against C3 convertase and on binding stabilizes
it. •The stabilized C3 convertase continuously drives the alternative
complement pathway, consuming complement. •As a consequence, patients have marked hypocomplementemia. |
| Epidemiology |
•The disease affects children and young adults
and is rare in older individuals. •May be seen following a respiratory
infection. •There is an association with partial lipodystrophy in some
cases. •Immunogenetics: DR7. |
| Clinical |
•Patients with membranoproliferative glomerulonephritis type II manifest
heavy proteinuria (3.5 gm or more per 24 hours) and the consequence of
protein loss (hypoalbuminemia, hyperlipidemia, edema). •Not infrequently
there is a nephritic component with red cells and red cell casts in the
urine sediment. •The disease is seen in children and young
adults. •Patients have marked hypocomplementemia, see pathogenesis. |
| General Gross Description |
•The kidneys in membranoproliferative glomerulonephritis type II, show no particular, nor distinctive gross abnormalities that reflect the pathologic process. |
| General Micro Description |
•The disease process is diffuse meaning that all glomeruli are
affected. •The glomerular tufts are globally hypercellular, usually to a
marked degree. •The cellularity is endocapillary meaning that the
proliferation of cells is within the tuft and not in the urinary
space. •There is lobular accentuation and individual segments can be
appreciated. •On the PAM silver stain for basement membranes, the
capillary loops may show a double contour or tram-track appearance. •With
the thioflavine T stain, ribbon-like fluorescent deposits may be seen
coursing along the contours of the glomerular and tubular basement
membranes. •Direct immunofluorescence studies show positive fluorescence
for C3 in a capillary loop pattern. •Electron microscopy shows ribbon-like electron dense deposits within the glomerular basement membranes and the tubular basement membranes. |
| Reference |
• Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp. 954-956. •Rose B. Renal Pathophysiology the essentials. Baltimore: Williams and Wilkins. 1994. Ch. 9.
|
