[Lupus cystitis and peritonitis successfully treated with intravenous cyclophosphamide pulse therapy: a case report].

A 35-year-old woman with systemic lupus erythematosus (SLE) experienced gastrointestinal and urinary symptoms, including lupus cystitis and peritonitis, which were initially treated with intravenous methylprednisolone. However, her symptoms recurred when the steroid dose was reduced. Subsequently, she was treated with monthly intravenous cyclophosphamide pulse therapy, which led to significant improvement in her symptoms and normalization of bladder and intestinal wall thickness. After five months, her steroid dosage was successfully reduced, and she was discharged. This case demonstrated that intravenous cyclophosphamide pulse therapy was an effective treatment for steroid-resistant lupus cystitis and peritonitis.