PLA2R-Antibody Positive Membranous Nephropathy; inflammatory demyelinating radiculopathy/ inflammatory demyelinating polyradiculopathy; joint pain; bilateral extremity paresthesias; marked edema; hypertension; over 20 lbs weight gain; weakness; unsteady gait; proteinuria; nephrotic syndrome; This serious case was reported in a literature article and described the occurrence of membranous nephropathy in a 56-year-old male patient who received Hepatitis B vaccine for prophylaxis.    Additional patient notes included No preceding illness.   On an unknown date, the patient received Hepatitis B vaccine. On an unknown date, less than a month after receiving Hepatitis B vaccine, the patient experienced membranous nephropathy (Verbatim: PLA2R-Antibody Positive Membranous Nephropathy) (serious criteria GSK medically significant), acute inflammatory demyelinating polyradiculopathy (Verbatim: inflammatory demyelinating radiculopathy/ inflammatory demyelinating polyradiculopathy) (serious criteria GSK medically significant), joint pain (Verbatim: joint pain), paresthesia of limbs (Verbatim: bilateral extremity paresthesias), edema (Verbatim: marked edema), hypertension (Verbatim: hypertension), weight gain (Verbatim: over 20 lbs weight gain), weakness (Verbatim: weakness), unsteady gait (Verbatim: unsteady gait), proteinuria (Verbatim: proteinuria) and nephrotic syndrome (Verbatim: nephrotic syndrome) (serious criteria GSK medically significant). The patient was treated with nsaid's (Nsaids (Unknown)) and prednisone. The outcome of the membranous nephropathy, proteinuria and nephrotic syndrome were resolved and the outcome of the acute inflammatory demyelinating polyradiculopathy and paresthesia of limbs were resolving and the outcome of the joint pain, edema, hypertension, weight gain, weakness and unsteady gait were not reported.   The reporter considered the membranous nephropathy, acute inflammatory demyelinating polyradiculopathy, joint pain, paresthesia of limbs, edema, hypertension, weight gain, weakness, unsteady gait, proteinuria and nephrotic syndrome to be related to Hepatitis B vaccine.     The company considered the membranous nephropathy, acute inflammatory demyelinating polyradiculopathy, joint pain, paresthesia of limbs, edema, hypertension, weight gain, weakness, unsteady gait, proteinuria and nephrotic syndrome to be related to Hepatitis B vaccine.   Additional Information: GSK Receipt Date: 04-MAY-2023 The patient was referred for a second opinion regarding membranous nephropathy (MN). He initially presented with joint pain and bilateral extremity paresthesias. He soon developed marked edema and hypertension, with over 20 lbs weight gain, associated with weakness and unsteady gait. No preceding illness was reported, but he had received hepatitis B vaccination one month prior. He had taken NSAIDs for pain but no other medications. He was found to have 17 grams of proteinuria/24 hs and was diagnosed with nephrotic syndrome. His renal function was normal. Serological workup including Complement factor C3/ Complement factor C4, antinuclear antibody (ANA), rheumatoid factor (RF), antineutrophil cytoplasmic antibody (ANCA), Anti-glomerular basement membrane (anti-GBM) antibodies, hepatitis panel, SPEP, UPEP was negative. A screening colonoscopy 6 years prior and a prostatic specific antigen level were normal. Renal biopsy showed membranous nephropathy. PLA2R was positive (1:40). Concomitantly, he was diagnosed with inflammatory demyelinating polyradiculopathy and was started on prednisone 60 mg daily. Over the next several months he showed neurological improvement, and the steroid dose was titrated down. Proteinuria also improved (less than 1g /24 hrs) and the nephrotic syndrome resolved. Repeat PLA2R levels have been negative.  This was the first case of MN associated with a inflammatory demyelinating radiculopathy with PLA2R positivity. The time correlation with the hepatitis B vaccination series raised the possibility that the HBV antigen triggered the autoimmune response. This article is not available for regulatory reporting due to copyright restriction.