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Medline ® Abstracts for References 1-6
of 'Glomerular diseases due to nonamyloid fibrillar deposits'

1
TI	Immunotactoid glomerulopathy.
AU	Korbet SM; Schwartz MM; Lewis EJ
SO	Am J Kidney Dis 1991 Mar;17(3):247-57.
	During the past 10 years, immunotactoid glomerulopathy has become recognized with increasing frequency. The lesion is characterized histologically by highly organized ultrastructural deposits that appear to be composed of immunoglobulin and complement and are negative for amyloid by Congo red stain. Clinically and/or serologically, patients have no evidence of cryoglobulinemia, amyloidosis, systemic lupus erythematosus, or a paraproteinemia, disorders associated with glomerular deposits, which also have a highly organized tactoidal or fibrillar characteristic. Immunotactoid glomerulopathy does not appear to be a multisystemic disease process and thus may represent a primary glomerulopathy. Patients with immunotactoid glomerulopathy present with proteinuria (nephrotic range in more than 60%) and over half of the patients have hypertension, hematuria, and renal insufficiency. Progression to end stage renal disease has occurred in more than 40% of patients reported to date. The experience in treating this disorder using prednisone and/or immunosuppression is limited and has not been impressive. Four patients have successfully undergone renal transplantation, but proteinuria recurred in two and was associated with the recurrence of immunotactoid glomerulopathy in the renal allograft. Although we have gained insight into the clinical course and histopathology of this disorder over the past few years, we still know little about its pathogenesis, an area for further research.
AD	Department of Medicine, Rush Presbyterian St. Lukes Medical Center, Chicago, IL.
PMID	1996564
2
TI	Fibrillary glomerulonephritis: an entity with unusual immunofluorescence features.
AU	Alpers CE; Rennke HG; Hopper J Jr; Biava CG
SO	Kidney Int 1987 Mar;31(3):781-9.
	We describe seven patients with renal biopsy findings of mild glomerular abnormalities on light microscopy but with prominent accumulation of randomly-arranged fibrillar material in the mesangium and capillary walls on electron microscopy. This material differed from amyloid in that fibrils were thicker (diameter range 10 to 19.5 nm) and did not stain with Congo Red. In six of seven cases fluorescence microscopy showed prominent staining for IgG and kappa light chain in mesangium and glomerular capillary walls; in three cases weak lambda chain staining was also present. Stains for IgA, IgM, and lambda chain were otherwise negative. One biopsy showed equal staining for kappa and lambda light chains, but not for heavy chain components. Clinical findings were heterogeneous. Patients presented with features of nephritis and/or nephrotic syndrome. No patient had an associated lymphoplasmacytic disorder, paraproteinemia, or other evidence of systemic disease. On follow-up ranging from five months to 12 years, all patients are still alive; six progressed to end-stage renal disease requiring dialysis. One patient developed recurrent disease in a renal allograft five years after transplantation. Non-amyloidotic fibrillary glomerulonephritis is an ultrastructurally distinct entity of undetermined etiology. The apparent association with monoclonal IgG and kappa light chain deposition observed in this series deserves further study.
AD
PMID	3106698
3
TI	Immunotactoid (microtubular) glomerulopathy: an entity distinct from fibrillary glomerulonephritis?
AU	Alpers CE
SO	Am J Kidney Dis 1992 Feb;19(2):185-91.
	Immunotactoid glomerulopathy (IT), or alternatively, microtubular glomerulopathy, is a term that has been used by some investigators to encompass those glomerulopathies characterized by the presence of fibrillar or microtubular deposits which are distinguished from amyloid principally by their larger size and lack of reactivity with the Congo red reagent. A case is presented here of IT as it was initially described. The present case, and a review of the literature, suggest that the diagnosis of IT be restricted to those glomerulopathies associated with large, at times organized, microtubular deposits. Terms such as fibrillary glomerulonephritis, or alternatively Congo red-negative amyloidosis-like glomerulopathy, could then be used to describe those patients with smaller, fibrillar glomerular deposits having an appearance closely resembling amyloid. We believe it is possible to separate the entities fibrillary glomerulonephritis and IT on morphological grounds. This is a potentially useful distinction that identifies patients who are likely to have or develop clinical evidence of a lymphoplasmacytic disorder or dysproteinemia, which are associated with deposits of IT, and distinguishes them from patients with fibrillary glomerulonephritis, of whom only a single case has been linked to such clinical findings.
AD	Department of Pathology, University of Washington School of Medicine, Seattle.
PMID	1739104
4
TI	Clinical and pathologic features of fibrillary glomerulonephritis.
AU	Iskandar SS; Falk RJ; Jennette JC
SO	Kidney Int 1992 Dec;42(6):1401-7.
	A diagnosis of fibrillary glomerulonephritis was made in 31 renal biopsies from 28 patients on the basis of the electron microscopic identification of glomerular deposits of randomly arranged fibrils that resembled amyloidosis but were larger. This accounted for approximately 1% of all nontransplant renal biopsy diagnoses. Renal biopsy specimens with parallel arrays of 30 nm to 50 nm microtubules (that is, immunotactoid glomerulopathy) were not included in the study. The patients had a mean age of 49 years with a range of 21 to 75. The male to female ratio was 1:1.8 and the ratio of Whites to Blacks was 8.3:1, which differs from the 3:1 ratio in our overall biopsy population. All patients had proteinuria (mean 6.0 g/day), and most had hematuria and renal insufficiency. After a mean follow-up of 24 months, there was 48% renal survival. The light microscopic appearance of the fibrillary glomerulonephritis was quite varied. Capillary wall thickening and matrix expansion were the most frequent alterations. Nineteen percent of specimens had crescents. Morphometric ultrastructural analysis demonstrated a mean fibril diameter of 22.4 +/- 7.4 nm. Immunofluorescence microscopy revealed that IgG was the dominant and often the only immunoglobulin class in immune deposits, and subclass analysis revealed that IgG4 was the dominant or exclusive subclass in all specimens tested. We hypothesize that the relatively homogeneous nature of the immunoglobulin in the immune deposits is the basis for the fibril formation.
AD	Department of Pathology, Bowman Gray School of Medicine, Wake Forest University, Winston Salem, North Carolina.
PMID	1474772
5
	Schwartz, MM, Korbet, SM, Lewis, EJ. Immunotactoid glomerulopathy. J Am Soc Nephrol 2002; 13:1390. no abstract available
6
TI	Fibrillary and immunotactoid glomerulonephritis: Distinct entities with different clinical and pathologic features.
AU	Rosenstock JL; Markowitz GS; Valeri AM; Sacchi G; Appel GB; D'Agati VD
SO	Kidney Int 2003 Apr;63(4):1450-61.
	BACKGROUND: Controversy surrounds the relatedness of fibrillary glomerulonephritis (FGN) and immunotactoid glomerulonephritis (IT). METHODS: To better define their clinicopathologic features and outcome, we report the largest single center series of 67 cases biopsied from 1980 to 2001, including 61 FGN and 6 IT. FGN was defined by glomerular immune deposition of Congo red-negative randomly oriented fibrils of<30 nm (mean, 20.1 +/- 0.4 nm). IT was defined by glomerular deposition of hollow, stacked microtubules of>or = 30 nm (mean, 38.2 +/- 5.7 nm). RESULTS: FGN comprised 0.6% of total native kidney biopsies and IT was tenfold more rare (0.06%). Deposits in FGN were immunoglobulin G (IgG) dominant and polyclonal in 96%. IgG subtype analysis in 19 FGN cases showed monotypic deposits in four (two IgG1 and two IgG4) and oligotypic deposits in 15 (all combined IgG1 and IgG4). In IT, deposits were IgG dominant in 83% and monoclonal in 67% (three IgG1 kappa and one IgG1 lambda). FGN patients were a mean age of 57 years, 92% were Caucasian, and 39% were male. At biopsy, FGN patients had the following clinical characteristics (mean, range): creatinine 3.1 mg/dL (0.5 to 14), proteinuria 6.5 g/day (0.8 to 25), 60% microhematuria, and 59% hypertension. Histologic patterns of FGN were diverse, including diffuse proliferative glomerulonephritis (DPGN) (nine cases), membranoproliferative glomerulonephritis (MPGN) (27 cases), mesangial proliferative/sclerosing (MES) (13), membranous glomerulonephritis (MGN) (four), and diffuse sclerosing (DS) (eight). The more proliferative (MPGN and DPGN) and sclerosing (DS) forms presented with a higher creatinine and greater proteinuria compared to MES and MGN. Median time to end-stage renal disease (ESRD) was 24.4 months for FGN and mean time to ESRD varied by histologic subtype: DS 7 months, DPGN 20 months, MPGN 44 months, compared to MES 80 months and MGN 87 months. There was no statistically significant effect of immunosuppressive therapy (given to 36% of FGN patients). By Cox regression (hazard ratio, confidence interval, P value), independent predictors of progression to ESRD were creatinine at biopsy [2.05 (1.55 to 2.72) P<0.001]and severity of interstitial fibrosis [2.01 (1.05 to 3.85) P = 0.034]. Although IT had similar presentation, histologic patterns, and outcome compared to FGN, it had a greater association with monoclonal gammopathy (P = 0.014), underlying lymphoproliferative disease (P = 0.020), and hypocomplementemia (P = 0.032). CONCLUSION: FGN is an idiopathic condition characterized by polyclonal immune deposits with restricted gamma isotypes. Most patients present with significant renal insufficiency and have a poor outcome despite immunosuppressive therapy, and outcome correlates with histologic subtype. By contrast, IT often contains monoclonal IgG deposits and has a significant association with underlying dysproteinemia and hypocomplementemia. Differentiation of FGN from the much more rare entity IT appears justified on immunopathologic, ultrastructural, and clinical grounds.
AD	Department of Pathology, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA.
PMID	12631361