[SLE with interstitial pneumonia during cyclophosphamide pulse therapy]

A 49 year-old man was admitted for edema and renal impairment due to SLE. Since he did not improve with predonisolone and methylprednisolone pulse therapy, cyclophosphamide pulse therapy (300 mg div.) was administered. The patient subsequently developed a fever, dyspnea and cough, and interstitial regions of the lungs exhibited shadows on X-ray and CT. The patient also suffered hypoxemia and poor lung function. Since several culture tests and viral antibody tests were negative for infection, antibiotics were not effective, and TBLB indicated interstitial pneumonia, which we speculated was induced by cyclophosphamide. However, this was such a severe case of interstitial pneumonia that it could not be cured merely by discontinuing the cyclophosphamide, but it did improve immediately after starting methylprednisolone pulse therapy. The incidence of cyclophosphamide-induced interstitial pneumonia is very low, but the mortality rate is high. Since cyclophosphamide pulse therapy is often used to treat SLE, attention should be focused on the incidence of interstitial pneumonia.