Membranous or membranous-like GN: A case report of massive proteinuria, positive serum with negative PLA2R on biopsy

Sixty‐five‐year‐old male with nephrotic syndrome underwent renal biopsy which showed features of membranous glomerulonephritis (MGN) on light and electron microscopy. He had positive serum anti‐PLA2R antibodies. Immunofluorescence revealed 2+ IgG4 and was negative for anti‐PLA2R. Membranous‐like glomerulonephritis was considered in differential along with membranous GN. Nephrotic syndrome is bread and butter for nephrology referral. It is defined as proteinuria >3.5 g/dL, edema, hypoalbuminemia, hyperlipidemia, and hyperlipiduria. MGN is one of the major causes of nephrotic syndrome. Predominant immunoglobulin (Ig) G granular pattern is seen in MGN with subclass IgG4 in idiopathic and non‐IgG4 subclass is prevalent in secondary MGN.1 C1q is suggestive of secondary MGN.1 We present a case showing features of membranous nephropathy, such as thick basement membrane and spike formation but showed only weak deposition of immunoglobulins (Ig) in the setting of nephrotic syndrome with 14 g of proteinuria. Amount of proteinuria was massive and disproportionate to the strength of positivity of IgG on immunofluorescence (IF). Positive anti‐PLA2R antibodies though they were checked 3 weeks after being on treatment helped point toward primary MGN.