Successful treatment by prednisolone for interstitial pneumonia associated with anagrelide in a patient with essential thrombocythemia

Anagrelide is a cytoreductive agent for essential thrombocythemia and its common side effects are anemia, headache, palpitation, diarrhea, and fluid retention. However, severe pulmonary adverse effects are rare. A 66-year-old Japanese man with essential thrombocythemia presented with hemoptysis 2 months after starting anagrelide treatment. Interstitial pneumonia was diagnosed based on physical and radiographic findings. Discontinuation of anagrelide and institution of corticosteroids resulted in the improvement of interstitial pneumonia. Severe lung injury associated with anagrelide is a rare but an important adverse event that must be addressed when treating interstitial pneumonia.