RESUMEN
We report an original case of a 27-year-old transgender woman who developed lupus nephritis after male-to-female sex reassignment surgery. The patient had been taking hormones to induce feminization since the age of 18. She was admitted with malar "butterfly" rash, anasarca and hypertension, associated with an increase in serum creatinine (1.7 mg/dl). Renal involvement was characterized by nephritic and nephrotic syndrome. Autoantibody tests were positive for antinuclear antibodies and anti-double-stranded DNA, and complement levels were markedly reduced. Renal biopsy demonstrated diffuse proliferative glomerulonephritis and granular immune complexes deposits with a "full-house" pattern at the immunofluorescence level. The induction treatment was realized with corticosteroid and cyclophosphamide and maintenance immunosuppression phase with mycophenolate, obtaining complete remission. We speculated that lupus nephritis was induced by estrogens and antiandrogen therapy and gonadectomy. In the present case, we discuss the role of sex hormones in systemic lupus erythematosus onset and review the cases linked to transgender patients.