Abstract

This report presents the uncommon case of a 47-year-old Bhutanese man diagnosed with concurrent bullous pemphigoid (BP) and anti-phospholipase A2 receptor (PLA2R)-negative Membranous nephropathy (MN). The patient initially presented with a two-year history of a Generalized, itchy, blistering rash, sparing mucosal areas, which was subsequently confirmed as BP via skin biopsy demonstrating sub epidermal blistering with eosinophilic infiltrate. Several Months prior to the current admission, he developed symptoms of nephrotic syndrome, Including generalized edema and frothy urine. A subsequent renal biopsy confirmed MN, Showing diffuse thickening of the glomerular basement membrane, granular IgG (predominantly IgG4) and C3 deposition, and sub epithelial electron-dense deposits, consistent with MN stage II-III. Notably, serum anti-PLA2R antibodies were negative (& lt; 2 RU/mL). Further investigations revealed hypoalbuminemia (2.0 g/dL), previous nephrotic-range proteinuria (7.93 g/24 hours), and excluded systemic lupus erythematosus and malignancy via negative autoantibodies and PET/CT scan, despite an elevated CA-125. Treatment included oral corticosteroids (Prednisolone, tapered from 40mg to 5mg daily) and tacrolimus (2mg twice daily), along with supportive care. The patient demonstrated a favorable response, with resolution of skin lesions And improvement in renal function, including normalization of serum creatinine. This case highlights the rare co-occurrence of BP and MN, particularly the diagnostic challenge presented by anti-PLA2Rnegative MN, necessitating consideration of alternative antigens and pathways. It underscores the importance of recognizing potential systemic autoimmune involvement in dermatological presentations and the need for multidisciplinary management.

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