A Case of Organizing Pneumonia Following Azacitidine Treatment for Myelodysplastic Syndrome

Organizing pneumonia (OP) is a lung pathology mainly affecting distal lung structures. Its etiology is often unknown, in which case it is termed cryptogenic organizing pneumonia (COP).  Of those cases of OP with an identified cause, the usual culprits include infections, medications, and radiation therapy. In this report, we present the case of a 73-year-old female on azacitidine –a pyrimidine analogue– used for treatment of myelodysplastic syndrome (MDS). The patient presented with fever, productive cough, and pleuritic chest pain. A CT of the chest, a bronchoalveolar lavage and a transthoracic biopsy were performed, and findings were consistent with OP, thought to be induced by azacitidine. The patient was treated with prednisone and subsequently showed significant improvement. Although rare, this case underlines the importance of considering OP in the context of non-resolving pulmonary infiltrates, particularly when there is a potentially relevant exposure, such as azacitidine.