HDCN Article Review/Hyperlink

Provonost PH, Brady HR, Gunning ME, Espinoza O, Rennke HG

Clinical features, predictors of disease progression and results of renal transplantation in fibrillary/immunotactoid glomerulopathy

Nephrol Dial Transplant (May) 11:837-842 1996

These authors report on 25 previously unpublished patients with fibrillary glomerulopathy (FG) / immunotactoid glomerulopathy (ITG), and review the literature covering 161 previously reported patients. FG/ITG were distinguished either by fibril diameter (FG < or = 30nm, ITG greater than 30 nm), or by arrangement (FG random, ITG focally organized).

Results revealed that more FG patients were female (1.3:1) while more males had ITG (1.4:1). FG Was much more common in Caucasians than in blacks (9:1). In both FG and ITG, proteinuria was universal, and nephrotic syndrome (70 - 86%), hematuria (64 - 75%), hypertension (45 - 85%) and renal insufficiency (42 - 54%)) were very common; no clear clinical picture differentiated between the two pathologic groups. When broken into groups with slow, intermediate, or rapid deterioration in renal function (by 1/Cr slope), patients who progressed more rapidly not surprisingly were more likely to be nephrotic and to have worse hypertension. Five renal transplants were performed in four patients, with recurrence of fibrillary deposits on graft biopsy in three. However the rate of transplant loss was much slower than that of the native kidneys, raising the question of whether the immunosupression modified the disease course. When patients with circulating or urinary paraproteins were included, malignancy was more common in patients with ITG (33%) vs. FG (7%), whereas if they were excluded the incidence of malignancy dropped to less than 7% in both groups.

Besides helping to better define the clinical picture of fibrillary and immunotactoid glomerulopathy, this paper suggests that transplantation may be a good option for patients with this condition. It further suggests that immunosupression may have a role in slowing the rate of the disease progression, particularly in patients who have been transplanted.

Comment: I agree with the author's suggestion not to overclassify this condition based purely on the fibrillar structure because the clinical illness, and degree of renal injury, seem similar in both groups (FG & ITG). Their suggested classification of glomerulopathy with extracellular fibrillary deposits seems prudent at the current time:
1) Amyloid-associated fibrillary glomerulopathy (congo-red positive),
2) Congo-red negative fibrillary glomerulopathy associated with cryoglobulinemia,
3)Congo-red negative fibrillary glomerulopathy in association with monoclonal gammopathy and
4) Congo-red negative idiopathic fibrillary glomerulopathy without measurable cryoglobulins or monoclonal gammopathy.

Whether or not glomerulopathy with congo-red negative fibrillary deposits represents a forme fruste of the similar disease in association with cryoglobulins or monoclonal gammopathy still remains an open question. (Stephen Pastan, M.D., Emory Clinic)