A case of interstitial pneumonitis associated with natural alpha-interferon therapy for myelofibrosis

A 55-year-old man with myelofibrosis was treated with natural alpha-interferon with a good hematologic response. Initially, he had anemia, leukocytosis, thrombocytosis and hepatospleomegaly. A bone marrow biopsy showed replacement with fibrosis with an increase in megakaryocytes. Natural alpha-interferon (alpha-IFN) was started at a dose of 3 x 10(6) units/day. The leukocyte and platelet counts gradually normalized, and the liver and spleen decreased in size. However, the patient complained of a dry cough and dyspnea on the 61st treatment day, when the accumulated dose of alpha-IFN treatment had reached 1.8 x 10(8) units. He subsequently developed acute respiratory failure (PaO2 < 60 mm Hg) with bilateral lung infiltrations, suggesting the occurrence of interstitial pneumonitis associated with alpha-interferon therapy. Immediately, the alpha-interferon was discontinued and high-dose methylprednisolone (1.5 g/day) was administered for 3 days. This treatment was followed by oral prednisone therapy. Steroid therapy brought about gradual improvement as suggested by a repeat radiograph. Since high levels of fibrogenic cytokines, such as PDGF and TGF-beta, have been reported in patients with myelofibrosis, it is necessary to pay attention to interstitial pneumonia as a complication in alpha-IFN therapy for myelofibrosis.