A Retrospective Clinicopathologic Study Of IgG Nephropathy And IgM Nephropathy

ObjectiveWe carried out a retrospective investigation of clinical pathological features of both IgGN and IgMN, in order to provide more evidence-based medical evidence for widespread controversy both existing in the two kinds of immune pathological diagnoses.The IgGN focuses on:(1) the difference of pathology, clinical manifestations and long-term prognosis between IgGN (MsPGN) and IgGN (FSGS); (2) the difference of pathology, clinical manifestations and long-term prognosis between IgGN (MsPGN) with and without IgA deposition; (3) relationship between IgGN and C1qN.IgMN focuses on:(1) the difference of pathology, clinical manifestations and long-term prognosis between IgMN (MsPGN) and IgMN (FSGS); (2) the difference of pathology, clinical manifestations and long-term prognosis between IgMN (MsPGN) IgM isolated deposit group and non-isolated deposit.Patients and MethodsA review of native kidney biopsies examined from 2001 through 2008 at the Kidney Institute of PLA, Chang Zheng Hospital, Second Military Medical University, identified IgGN in 62 patients and IgMN in 100 patients. According to glomerular light microscopic morphological features both IgGN and IgMN were divided into two categories:MsPGN category and FSGS category. According to whether deposit of IgA was identified on immunofluorescence microscopy or not, IgGN(MsPGN) was further subdivided into two groups:IgGN(MsPGN) IgA(-) group and IgGN(MsPGN) IgA(+) group. According to whether deposit of IgM was identified isolated on immunofluorescence microscopy or not, IgMN(MsPGN) was further subdivided into two groups:IgMN(MsPGN) Isolated group and IgMN(MsPGN) Non-Isolated group.Results1 IgGN (FSGS) showed significantly lower percetage of moderate to severe mesangial matrix proliferation, severe tubulointerstitial and small vessel lesions disease than IgGN (MsPGN).2 Patients with mainly mesangial IgG deposition accompanied by mild mesangial IgA deposition (≤1+) could be classified into IgGN (MsPGN). Patients with IgG and IgA co-deposition could be diagnosed as IgGN (MsPGN) as long as (1) fluorescence intensity of IgG≥IgA; (2) IgA≤1＋.3 The vast majority of cohorts concerning C1qN did not include patients with IgG≥C1q; while 57% of patients with IgGN (MsPGN) had the fluorescence intensity of C1q≥IgG. Therefore, (1) the patient should be diagnosed as IgGN(MsPGN) when IgG>C1q; (2) C1qN when C1q>IgG; (3) IgGN (MsPGN) when IgG=C1q.4 IgMN (FSGS) showed significantly higher proportion of non-isolated IgM deposition than IgMN (MsPGN), C3 deposition, more severe tubular interstitial small vessel lesions, longer duration from onset of disease to receiving biopsy, higher MAP, lower LDL level, higher lever of uric acid, urea nitrogen, serum creatinine, and higher percentage of patients with CKD≥3 periods, lower lever of MDRD-GFR and CKD-EPI, higher percentage of progression of renal disease than IgMN (MsPGN).5 IgMN (MsPGN) IgM non-isolated group showed higher incidence of hypertension and NS higher than IgMN (MsPGN) IgM isolated group. Small differences of clinicopathological characteristics between the two groups could explain the alike small differences of percentage of progression of kidney disease and ESRD. Therefore, there was no significance of other immune globulin and (or) complement deposits with low intensity in IgMN (MsPGN).6 IgGN patients showed much more severe of mesangial matrix proliferation and cell proliferation than IgMN. Mesangial matrix proliferation was much more severe than cell proliferation in IgGN than IgMN. Mesangial matrix proliferation was also much more severe than cell proliferation in IgGN (MsPGN) than IgMN (MsPGN). On the contrary, the degree of proliferation of mesangial matrix in patients with IgMN was the same as the degree of mesangial cell proliferatione, both were relatively moderate.ConclusionIgGN (FSGS) showed significantly lower percetage of moderate to severe mesangial matrix proliferation, severe tubulointerstitial and small vessel lesions disease than IgGN (MsPGN). The patients with mesangial IgG deposition mainly accompanied by mild mesangial IgA deposition (≤1+) could be classified as IgGN (MsPGN). When the immune pathology results showed that IgG and C1q co-deposition, therefore, (1) the patient should be diagnosed as IgGN(MsPGN) when IgG>C1q; (2) C1qN when C1q>IgG; (3) IgGN (MsPGN) when IgG=C1q. There were many obvious clinical and pathological heterogeneity between IgMN (FSGS) and IgMN (MsPGN). With or without a low intensity deposition of other immune globulin and (or) complement, IgMN showed the similar clinical and pathological performance, and long-term prognosis.