Nephrotic syndrome developing in association with thymoma and myasthenia gravis

Abstract

Three patients with thymoma associated myasthenia gravis complicated by the nephrotic syndrome are described. There were two male and one female patients with a mean age at presentation of 55.6 years (27–75). In all cases anti striated‐muscle and acetylcholine‐receptor antibodies were present. Thymectomy was performed 1.4 years (1–3) after diagnosis of myasthenia gravis; histology revealed invasive mixed lymphocytic/epithelial (1), invasive epithelial (1) and non‐invasive lymphocytic/epithelial (1) cell thymoma. All patients were receiving pyridostigmine, prednisolone and azathioprine at the time nephrotic syndrome developed (a mean of 2 years after thymectomy). Renal biopsy demonstrated a minimal change nephropathy alone in all three. Remission following increased steroids occurred in two despite continuing azathioprine. Myasthenic symptoms remained stable throughout. The third patient died 3 weeks after onset of nephrotic syndrome. The cause of the nephrotic syndrome is uncertain, but an immune mechanism, possibly in genetically predisposed individuals, is perhaps most likely.