Focal and Segmental Glomerulosclerosis and Membranous Nephropathy overlapping in a patient with Nephrotic Syndrome: a case report

Abstract Introduction: Some cases of membranous nephropathy (MGN) present focal segmental glomerulosclerosis (FSGS) typically associated with disease progression. However, we report a case of a patient who seemed to have MGN and FSGS, both primary. Case presentation: A 17-year-old female, Caucasian, presenting lower extremity edema associated with episodes of foamy urine and high blood pressure, had physical and laboratorial exams indicating nephrotic syndrome. A renal biopsy was performed and focal and segmental glomerulosclerosis were observed under light microscopy in some glomeruli presented as tip lesion, and in others it was accompanied by podocyte hypertrophy and podocyte detachment in urinary space, compatible with podocytopathy FSGS. Besides, there were thickened capillary loops with basement membrane irregularities due to "spikes" compatible with MGN stage II. Immunofluorescence showed finely granular IgG, IgG4, and PLA2R deposits in capillary loops and, in electron microscopy, subepithelial deposits and foot process effacement. These morphological findings are compatible with FSGS and MGN stage II. Conclusions: In the present case, clinical and morphological characteristics showed a possible overlap of primary FSGS and MGN as focal and segmental glomerulosclerosis does not seem to be related with MGN progression but with the podocytopathy FSGS.

摘要 引言：部分膜性肾病（membranous nephropathy, MGN）病例可出现局灶节段性肾小球硬化症（focal segmental glomerulosclerosis, FSGS），该表现通常与疾病进展相关。然而本文报告1例同时疑似原发性膜性肾病与原发性局灶节段性肾小球硬化症的患者。病例报告：1例17岁白人女性患者，临床表现为下肢水肿，伴反复泡沫尿及高血压，体格检查与实验室检查结果符合肾病综合征表现。遂行肾活检术，光学显微镜下可见部分肾小球呈现局灶节段性硬化，表现为顶端病变；其余肾小球可见足细胞肥大、足细胞脱落至尿腔，符合足细胞病型局灶节段性肾小球硬化症特征。此外，可见毛细血管袢增厚，基底膜因“钉突”形成而不规则，符合Ⅱ期膜性肾病表现。免疫荧光检测显示毛细血管袢内可见细颗粒状IgG、IgG4及PLA2R沉积；电子显微镜下可见上皮下电子致密物沉积及足突广泛融合。上述形态学表现同时符合Ⅱ期膜性肾病与局灶节段性肾小球硬化症的诊断标准。结论：本病例的临床与形态学特征提示原发性局灶节段性肾小球硬化症与膜性肾病可能存在重叠现象，本次观察到的局灶节段性肾小球硬化表现似乎并非与膜性肾病进展相关，而是与足细胞病型局灶节段性肾小球硬化相关。