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| 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. |
| General Gross Description •The kidneys in membranoproliferative glomerulonephritis type II, show no particular, nor distinctive gross abnormalities that reflect the pathologic process. |
| General Microscopic 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. |
| Clinical Correlation •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. |
| References • 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. |
| Membranoproliferative Glomerulonephritis Type II |
| Synopsis by: Harold Yamase M.D. (T71200M00013)[214] |
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