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Abstract: PO1899

Etiology, Histology, and Prognosis of Primary and Secondary Membranous Nephropathy in Young Patients Under 50 Years Old: A 35-Year, Two-Center Experience

Session Information

Category: Glomerular Diseases

  • 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Oda, Yasuhiro, Toranomon Hospital Kajigaya, Kawasaki, Kanagawa, Japan
  • Yamanouchi, Masayuki, Toranomon Hospital Kajigaya, Kawasaki, Kanagawa, Japan
  • Suwabe, Tatsuya, Toranomon Hospital Kajigaya, Kawasaki, Kanagawa, Japan
  • Hoshino, Junichi, Toranomon Hospital Kajigaya, Kawasaki, Kanagawa, Japan
  • Ubara, Yoshifumi, Toranomon Hospital Kajigaya, Kawasaki, Kanagawa, Japan
Background

Membranous nephropathy (MN) is often diagnosed in older age group; its mean age of onset is 50-60 years old. Although retrospective analyses on young patients with primary MN have been published, clinicopathologic characteristics of primary MN and secondary MN combined in young patients have not been reported.

Methods

All patients diagnosed with MN in the age under 50 years old by a kidney biopsy performed between January 1985 and December 2019 at Toranomon Hospital and Toranomon Hospital Kajigaya were retrospectively analyzed. All patients with glomerular membranous changes presumed to be due to subepithelial deposits were included except for cases with classic membranoproliferative glomerulonephritis.

Results

37 patients met the criteria. 19 of them (51%) had nephrotic syndrome, 17 (46%) had urinary protein excretion less than 3.5 grams per day, and one (3%) had no proteinuria. To evaluate renal biopsy specimens, light microscopy was performed in all cases, fluorescence microscopy in 36 cases and electron microscopy (EM) in 28 cases. 14 patients (38%) were diagnosed with primary MN, 22 patients (59%) with secondary MN, and one patient (3%) with de novo MN post-transplantation. Secondary MN were due to lupus erythematosus (27%), mixed connective tissue disease (14%), Sjögren's syndrome (3%), hepatitis B (11%), bucillamine use (3%), and graft versus host disease (GVHD) after peripheral blood stem cell transplantation (3%). Mean and median follow-up period was 14.9 and 12.0 years, respectively. At the end of follow-up, only two patients out of the 37 patients reached end-stage renal disease, and 33 patients (89%) observed serum creatinine level lower than 1.5 mg/dL. 21 patients achieved complete remission (CR). Among 27 cases who underwent EM, cases with subendothelial deposits had smaller CR rate (3/11 cases) than those without subendothelial deposits (12/16 cases), which was statistically significant (χ2=6.01, p=0.014). The CR rates of cases with mesangial deposits (12/21 cases) and those without mesangial deposits (3/6) was not significantly different (χ2=0.096, p=0.76).

Conclusion

The prognosis of renal function was fairly good in patients with MN in the age under 50 years old. Cases with coexisting subendothelial deposits showed lower CR rate than the rest.