Focal segmental membranous glomerulonephropathy associated with other glomerular diseases

Diagnostic and prognostic significance of extent of subepithelial electron dense deposits in membranous glomerulonephritis

There are limited data concerning the range and diagnostic significance of the extent of subepithelial electron dense deposits (SEEDD) in membranous glomerulonephritis (MGN). We described the range, and assessed the diagnostic and prognostic significance of extent of SEEDD, particularly in patients with sparse SEEDD, where diagnostic difficulty can arise. Adult renal biopsies with a confident or suspected histological diagnosis of MGN between 2013 and 2020 were included. Patients were classified based on extent of SEEDD as having either global MGN (GMGN, >75% SEEDD), segmental MGN (SMGN, 25%-75% SEEDD), or sparse-SEEDD (<25% SEEDD). Clinical and other features were compared. One hundred and eleven (74%) patients had GMGN; 23 (15%) had SMGN; and 16 (11%) had sparse-SEEDD. Patients with sparse-SEEDD had a significantly shorter duration of nephrotic syndrome prior to biopsy. 53% of patients with GMGN and 14% with SMGN had serum anti-phospholipase A2 receptor (PLA2r) antibodies. Patients with sparse-SEEDD did not have anti-PLA2r antibodies. Urine protein:creatinine ratio was significantly lower in sparse-SEEDD patients after 3, 6, 9, and 12 months. The proportion of sparse-SEEDD patients in complete remission from nephrotic range proteinuria at 6 and 12 months was significantly higher than that of GMGN patients. Analysis of a subgroup suggested sparse-SEEDD patients responded more rapidly to steroid containing immunosuppression than GMGN patients. There is a wide range of extent of SEEDD in patients with MGN. Sparse-SEEDD appears distinct from SMGN and GMGN and may be either an early form of MGN, or an epiphenomenon associated with another primary disease process, particularly minimal change disease.

Segmental membranous nephropathy

Most cases of membranous nephropathy (MGN) present with global and diffuse distribution of subepithelial deposits. However, segmental MGN, in which there is focal or diffuse segmental subepithelial deposits, are occasionally encountered. The clinical and pathologic significance of segmental MGN is not well understood and thought to be more likely due to either early or resolving phase of the global form of MGN. Several case reports and literature available suggest that it may be a manifestation of secondary causes based on pathologic features such as presence of C1q and mesangial deposits, extra-glomerular deposits involving tubular basement membranes, absence of PLA2R and THSD7A, IgG1 and IgG3 subclass dominance, and the presence of other co-existing renal disease. Other reports, however, suggest that some of these cases may be a variant of the primary form of MGN. In this review, we integrate what is known about segmental MGN in order to better direct interpretation of renal biopsies in which it is identified.

The clinicopathologic spectrum of segmental membranous glomerulopathy

Membranous glomerulopathy (MGN) is characterized by global subepithelial immune deposits that stain most intensely by immunofluorescence for IgG. Here we describe the clinical and pathologic findings in a cohort of patients with MGN in which, by definition, only segmental immune deposits are present. This rare variant, termed segmental MGN (sMGN), is poorly characterized. We retrospectively identified all patients with sMGN diagnosed at Columbia University from January 2010 to October 2018, excluding those with systemic lupus erythematosus. Data on presenting features, pathologic findings, and outcomes were collected. Fifty cases of sMGN were identified, representing 2.5% of MGN. In 21 of 50 biopsies, there was an alternative, predominant disease process. The remaining 29 patients with isolated sMGN had a median creatinine of 0.97 mg/dl, median 24-hour urine protein 3.1 g/day, and 32% had nephrotic syndrome. Staining for NELL-1 (a protein kinase C binding protein) was positive in five of 17 cases. Staining for PLA2R, THSD7A, and exostosin 1 (autoantigens in primary MGN) was negative in all biopsies evaluated. Ultrastructural evaluation revealed predominantly early stage sMGN (stage 1 or 1-2 in 14/29). Follow-up was available for 21 of the 29 patients with isolated sMGN (median 12 months), including seven who received immunosuppression (primarily glucocorticoids). During follow-up, 86% had stable/improved kidney function and 45% achieved complete while 15% achieved partial remission. Among the 15 patients with isolated sMGN without full nephrotic syndrome, only two received immunosuppression; nonetheless, 50% achieved complete while 21% achieved partial remission. Thus, sMGN is a rare PLA2R-negative variant of MGN with 29% NELL-1 positivity and favorable prognosis, even in the absence of immunosuppressive treatment.

A Rare Adult Case with Diffuse Segmental Membranous Glomerulonephritis

A 71-year-old man with hypertension and diabetes mellitus presented with proteinuria. Laboratory data showed proteinuria of 3.1 g/g creatinine, serum albumin of 3.5 g/dL and serum creatinine of 1.03 mg/dL without autoantibodies. A renal biopsy revealed segmental granular IgG depositions on glomerular capillary walls. Electron microscopy showed segmentally subepithelial, intramembranous and mesangial deposits. Diffuse segmental membranous glomerulonephritis (MGN) was diagnosed with only IgG1 deposition and without M-type phospholipase A2 receptor or thrombospondin type-1 domain-containing 7A staining, suggesting secondary MGN with an unknown target antigen in immune deposits. Physicians should keep in mind the existence of segmental MGN to better understand the clinicopathological characteristics.

Pattern of double glomerulopathy in children

Occasional case reports have been issued on children with double glomerulopathy, involving either the coexistence of two different glomerulopathies or superimposition of a second glomerulopathy onto a first. A retrospective clinicopathological review of 294 children who had received renal biopsies resulted in 9 (3.1%) being confirmed to have double glomerulopathy. Superimposed glomerulopathy was diagnosed by a second renal biopsy in two cases, and coexistence of two glomerulopathies was confirmed by single biopsy in seven. Original glomerulopathies were those with a chronic course, such as Alport syndrome, IgA nephropathy, relapsing minimal-change nephrotic syndrome, Frasier syndrome, and thin basement membrane nephropathy. The superimposing glomerulopathies were common types in children, such as postinfectious glomerulonephritis, IgA nephropathy, and Henoch-Schönlein nephritis. Thus, the pattern of double glomerulopathy was considered to be due to the chance occurrence of two different glomerulopathies without a common pathogenesis. Acute nephritic symptoms of superimposed glomerulopathies resolved almost completely during follow-up in most cases. Double glomerulopathies are not rare in children and may occur by chance alone in most cases. The possibility of superimposed glomerulopathy should be suspected if the clinical course of a glomerulopathy changes atypically. However, the long-term influence of a superimposed glomerulopathy on renal functional deterioration remains unclear.

Segmental Membranous Glomerulonephritis in Children: Comparison with Global Membranous Glomerulonephritis

Generally, idiopathic membranous glomerulonephritis (MGN) is a global glomerular disease that affects the whole of the glomerulus. However, idiopathic segmental MGN (SMGN) that shows IgG deposits in a portion of the glomerulus is encountered often. For clarification of whether SMGN is the same entity as idiopathic global MGN (GMGN), the two diseases were compared. From 1978 to 2004, 38 children (11 with SMGN and 27 with GMGN) received a diagnosis of idiopathic MGN. Immunofluorescence microscopy showed segmental granular IgG staining along the capillary loops in SMGN, whereas GMGN showed global staining. On light microscopy, SMGN showed segmental thickening of the glomerular basement membrane, with spike formation, whereas GMGN showed global lesions. The frequency of C1q deposits in SMGN was significantly higher than that in GMGN (91 versus 41%; P < 0.01). On electron microscopy, mesangial electron-dense deposits were detected in 10 (91%) cases of SMGN and also were found in the subepithelial and intramembranous area, whereas only six (22%) cases of GMGN had mesangial electron-dense deposits (P < 0.001). There were no significant differences in clinical features between the groups. Two children with SMGN underwent a repeat biopsy 3 yr after the first biopsy, and both patients again showed SMGN. At the final observation (mean observation time 7.5 yr in SMGN and 12.4 yr in GMGN), all children of both groups had a good outcome. In conclusion, these findings as a whole suggest that SMGN may be another glomerular disease entity with child predominance that is distinctive from GMGN.

Prospective study on renal outcome of IgA nephropathy superimposed on diabetic glomerulosclerosis in type 2 diabetic patients

BACKGROUND AND METHODS

In order to examine the clinical outcome of IgA nephropathy (IgAN) superimposed on diabetic glomerulosclerosis in type 2 patients we studied 36 Chinese patients (26 men, 10 women), who were recruited for renal biopsy when they had proteinuria of more than 1 g/day. Twenty-seven had isolated diabetic glomerulosclerosis and nine had IgAN superimposed on diabetic glomerulosclerosis (combined). Renal function was assessed by serial serum creatinine, 24-h urine protein and creatinine measurements. Patient survival rate, incidence of end-stage renal disease (ESRD), blood pressure, and glycaemic control status were determined.

RESULTS

The age at the time of renal biopsy was younger for the combined group when compared with the diabetic glomerulosclerosis group (44+/-3.6 vs 58+/-2.1 years, P=0.006). The duration of diabetes was, however, similar for the two groups (8.0+/-2.3 vs 6.7+/-1.2 years, P=NS). After a mean follow-up of 31.6+/-15.3 months, 15 patients (one in the combined group and 14 in the diabetic glomerulosclerosis group) developed ESRD. Nine patients (all in the diabetic glomerulosclerosis group) died during follow-up. With similar glycaemic and blood pressure control, the two groups had comparable rate of decline of creatinine clearance (CrCl) (-0.73+/-0.26 vs -0.73+/- 0.18 ml/min/1.73 m(2)/month, P=NS), final serum creatinine (363+/-134 vs 426+/-52 micromol/l, P=NS) and proteinuria levels (4.3+/-0.9 vs 4.4+/-0.6 g/day, P=NS), as well as CrCl (44.1+/-19.0 vs 33.4+/-6.9 ml/min/ 1.73 m(2), P=NS).

CONCLUSION

It is concluded that the superimposed IgAN does not significantly alter the medium-term clinical outcome of patients with diabetic glomerulosclerosis.

Clinicopathological characteristics of the focal and segmental form of idiopathic membranous nephropathy: comparison with the typical form of this disease

Although idiopathic membranous nephropathy (IMN) is thought to represent a diffuse glomerulopathy, it was found that three of 31 children histologically diagnosed as IMN showed focal and segmental deposition of immunoglobulin G (IgG) and C3 on the glomerular capillary walls. The present study attempted to comparatively investigate clinical and pathological features of the diffuse group and the focal segmental group in 31 IMN children. Immunofluorescence study revealed that 28 of 31 IMN exhibited diffuse granular deposition of IgG along glomerular capillary walls. In contrast, focal and segmental deposition of IgG and C3 was noted in three children with IMN. In addition, focal and segmental electron-dense deposits were identified in these cases. In two children of the focal segmental group, immunofluorescent patterns of IgG deposition were unchanged even at the second biopsy. The focal segmental form of IMN tended to occur in younger children than diffuse IMN. However, other clinical parameters such as the range of proteinuria, hematuria, serum albumin and prognosis did not show any significant differences between both groups. Electrophoretic profiles of urinary proteins on sodium dodecylsulfate-polyacrylamide gel electrophoresis were not different between both groups. It is proposed that the focal segmental form of IMN may have a distinctive glomerulopathy from the typical form of IMN.

Focal glomerulosclerosis in idiopathic membranous glomerulonephritis

The significance of the finding of focal glomerulosclerosis (FGS) in idiopathic membranous glomerulonephritis (MGN) is uncertain. Twenty-seven patients with mixed FGS and MGN (MGN-FGS) were compared to 25 patients with MGN alone (generally matched for age, sex and stage of glomerular lesion) with respect to pathology, presenting clinical and laboratory features, and course of disease. Biopsies from the MGN-FGS patients showed significantly more extensive tubulointerstitial disease (P less than 0.001) than did those with MGN alone. At the time of biopsy, the MGN-FGS group had a significantly higher proportion of patients with hypertension (P = 0.006) and microhematuria (P = 0.006), a marginally higher percentage of patients with the nephrotic syndrome (P = 0.051), and a greater mean 24-hour urinary protein excretion (P = 0.004). A similar proportion of patients in each group were treated with either prednisone alone or prednisone with an immunosuppressive. Forty-eight percent of MGN-FGS patients and 13% of the MGN patients developed established renal failure in the follow-up period (P = 0.008). The renal survival rate for the MGN-FGS group was significantly lower at 24 months (0.61 vs. 0.93, P less than 0.05), 60 months (0.48 vs. 0.88, P less than 0.025), and over the entire follow-up period (P less than 0.05). The results indicate that FGS in MGN is associated with a significantly poorer prognosis than MGN without this lesion.

The association of IgA glomerulonephritis and thin glomerular basement membrane disease in a hematuric patient: light and electron microscopic and immunofluorescence investigation

A double glomerulopathy (IgA glomerulonephritis [IgAGN] associated with thin glomerular basement membrane disease [TGBMD]) is reported in a 39-year-old woman presenting with macroscopic-microscopic hematuria. Her 3-year-old daughter was also affected by microhematuria of probable glomerular origin. The diagnosis of IgAGN was made by means of immunofluorescence investigation, which showed generalized diffuse mesangial deposits. TGBMD was identified by electron microscopic investigations, which disclosed thinning (up to 160 nm) of basement membrane of several capillary loops and prominence of the lamina densa. Bearing in mind the known frequencies of the two glomerulopathies, their association may not be coincidental, and, therefore, is worthwhile researching in hematuric patients.

De novo membranous glomerulonephropathy in renal allografts: a report of ten cases and review of the literature

De novo posttransplantation membranous glomerulonephropathy (MGN) is the most common form of de novo glomerulopathy in renal allografts. The clinical and pathological features of ten patients with de novo MGN were studied and the related literature was reviewed to assess the clinical features, morphologic characteristics, and natural course of this disease. De novo MGN may occur in both living related and cadaveric allografts at any time after transplantation. It presents clinically either as asymptomatic proteinuria or the nephrotic syndrome, a feature of poor prognostic implication. Morphologically, de novo MGN in most instances has distinct differences from idiopathic MGN in native kidneys and is accompanied by varying features of rejection. About 50% of grafts which develop de novo MGN eventually fail. This rather poor outcome may not represent the natural history of de novo MGN per se but rather the consequences of associated chronic rejection. Evidence is presented that many of the cases of so-called de novo MGN may be a complication of transplant glomerulopathy rather than being caused by mechanisms totally independent from rejection.

Juvenile renal disease in the Doberman Pinscher: ultrastructural changes of the glomerular basement membrane

Ten cases of juvenile renal disease in Doberman Pinschers were examined by light microscopy and 8 of them additionally by electron microscopy. Two distinct basic ultrastructural lesions of the glomerular basement membrane (GBM) were observed. One is characterized by lamellation of the lamina densa with intramembranous focal areas of lucency containing electron-dense particles, the second by diffuse attenuation of the lamina densa with intramembranous and/or subendothelial deposition of matrix entrapping cross-banded fibres (collagen). Based on similar ultrastructural changes in other hereditary nephropathies in man and dogs, a metabolic or biochemical basis for the structural lesions is suspected.

Superimposed nephritis: a separate entity among glomerular diseases?

The concomitant occurrence of two glomerular diseases in the same patient was diagnosed in seven out of 105 patients undergoing renal biopsy for suspected glomerulopathy. The most frequently associated disease was a membranous type glomerulopathy. The follow-up was characterized by a rapid deterioration of renal function and two patients were required to start a chronic hemodialysis program soon after the diagnosis. It is suggested that the observed coexisting patterns of glomerular injury do not occur on the basis of chance alone and should be considered as a separate entity in glomerular pathology. In all cases, clinical and pathologic findings were strongly suggestive for two consecutive distinct pathologic processes, thus justifying the use of the term superimposed nephritis. It is reasonable to assume that the mechanisms responsible for glomerular damage and for the evolution of the disease in superimposed nephritis are different from those regulating the corresponding glomerulonephritis when occurring alone. The high prevalence of membranous pattern in superimposed nephritis indicates that pre-existing glomerular alterations might favor an immune reaction in the subepithelial space.

Segmental subepithelial deposits in primary glomerulonephritis: scanning electron microscopic examination of acellular glomeruli

More accurate perception of the structural alterations in glomerular basement membrane (GBM) produced by subepithelial immune complex deposits is possible with a recently adapted technique that uses scanning electron microscopy of acellular material. With this procedure frozen tissue is treated sequentially by osmotic lysis, detergents, and DNase to solubilize both cellular components and immune complex deposits. Four patients with glomerulonephritis (acute postinfectious glomerulonephritis [one patient], segmental membranous glomerulonephritis [two patients], membranoproliferative glomerulonephritis, type III [one patient]) in whom segmental subepithelial deposits were found were studied by this technique; the resulting observations were correlated with the results of routine morphologic studies and a previous study of minimal change disease and diffuse membranous glomerulonephritis. Four types of structural alterations of the subepithelial GBM surface were observed. The differences in lesions observed in the various forms of glomerulonephritis are believed to be related to temporal, quantitative, and qualitative differences in immune complex-mediated glomerular injury.

Coexistence of IgA nephropathy and membranous nephropathy

Renal biopsy findings of a 27-year-old female with asymptomatic proteinuria and hematuria revealed two distinct glomerular alterations compatible with both IgA nephropathy and membranous nephropathy. The concomitant presence of two different primary glomerular diseases is very rare.

The changing natural history of nephropathy in type I diabetes

Events in the natural history of diabetic nephropathy (including the onset of persistent proteinuria and end-stage renal failure) were studied in a cohort of 292 patients with juvenile-onset type I diabetes who were followed for 20 to 40 years. The risk of persistent proteinuria increased rapidly between the fifth and 15th years of diabetes and declined thereafter. This pattern suggests that susceptibility to this complication was limited to a subset of patients and was exhausted over time. Patients with the most frequent severe hyperglycemia (the highest quartile) during the first 15 years of diabetes had a risk of persistent proteinuria that was four and a half times higher than that for those with the least frequent hyperglycemia (the lowest quartile). Patients whose diabetes was diagnosed in the 1930s had twice the risk of persistent proteinuria as those in whom the condition was diagnosed in later decades. Once persistent proteinuria appeared, progression to renal failure almost always followed. Half reached this stage within 10 years, and the interval for progression did not vary according to sex, frequency of hyperglycemia, or calendar year of diagnosis of diabetes. This period, however, was significantly shorter (eight versus 14 years) for patients whose diabetes was diagnosed after puberty than for those who were younger at onset. In conclusion, the development of diabetic nephropathy consists of at least two stages. The onset of proteinuria, although related to the level of exposure to hyperglycemia, appears to be influenced by genetic and/or environmental factors. The second stage, progression to renal failure, seems to be influenced by processes related to maturation or aging.

Association of IgA nephropathy with steroid-responsive nephrotic syndrome. A report of the Southwest Pediatric Nephrology Study Group

In a multicenter study of 83 children with IgA nephropathy, we have encountered four patients (three female, one male) who presented with steroid-responsive nephrotic syndrome (NS) 1 to 12 years before the demonstration of IgA nephropathy. Renal biopsies performed within several months of the onset of NS in three of the patients showed changes consistent with minimal change glomerulonephropathy in two and diffuse mesangial hypercellularity in one patient. Immunofluorescence studies performed on two of the biopsies were negative for IgA. Corticosteroid therapy induced remission of NS in all four patients, but this was followed by frequent relapses. IgA nephropathy was diagnosed subsequently by renal biopsies that were performed because of the onset of gross hematuria in three patients and persistent, low-grade proteinuria in the other. Light microscopy studies on these biopsies showed minimal glomerular changes in three and focal proliferative and sclerosing glomerulonephritis in one patient. Subsequent follow-up evaluations have revealed normal serum creatinines and/or glomerular filtration rate (GFR) in all four patients with remission of NS in three and no further episodes of gross hematuria in any patient. These four patients represent either a variant of IgA nephropathy associated with long-standing steroid-responsive NS or development of IgA nephropathy superimposed upon preceding minimal change disease.