LAUSR

A 28-year-old male in the first complete remission of acute myeloid leukemia underwent unrelated umbilical cord blood transplantation (3.49 × 107 kg−1 nucleated cells) from a human leukocyte antigen 3/8 mismatched donor. Pre-transplant conditioning consisted of fludarabine [30 mg/m2, days 7 to 2], intravenous busulfan [3.2 mg/kg, days 7 to 4], and melphalan [40 mg/m2, days 3 to 2], and GVHD prophylaxis consisted of tacrolimus and short-term methotrexate. The patient engrafted neutrophils on day 19, and grade I acute GVHD (skin stage 1, liver stage 0, and gut stage 0) developed on day 25 and was successfully treated with oral corticosteroid. He developed high fever over 39 °C (maximum 39.6 °C) on day 38, and subsequently dyspnea from day 40. Oxygen support of 5 L/min with facemask was required to maintain arterial oxygen saturation above 95%. He showed elevated peripheral blood leukocyte (24,300 μl−1) and eosinophil counts (10,570 μl−1). Plasma β-d-glucan, serum Aspergillus antigen, and T-SPOT.TB were all negative. Thoracic computed tomography (CT) scan showed bilateral diffuse centrilobular nodules of several millimeters, and much larger nodular lesions prominent in peripheral area (Fig. 1). Analysis of bronchoalveolar lavage (BAL) cells revealed increased eosinophils (17.8% of all nucleated cells). Microbiological studies of BAL fluid were all negative, including Gram staining, bacterial cultures, and polymerase chain reaction targeting adenovirus, cytomegalovirus, human herpes virus 6, and varicella zoster virus. Although prophylactic oral levofloxacin and voriconazole had been given since day 30, no additional drugs were started within 3 weeks prior to onset of dyspnea, ruling out drug-induced pneumonitis. A diagnosis of acute eosinophilic pneumonia (AEP) was made and systemic steroid therapy with methylprednisolone (1000 mg for three days) was initiated on day 45. His respiratory symptoms and radiographic findings improved quickly (Fig. 2), and he was discharged from the hospital on day 66 posttransplant after steroid tapering. Acute eosinophilic pneumonia is an acute febrile illness with respiratory impairment, diffuse pulmonary infiltrates, and eosinophilia in the BAL fluid. While there are a few reports of AEP after hematopoietic stem cell transplantation, diffuse peripheral ground-glass opacity, thickened interlobular septa, and pleural effusion are typical findings on CT images of AEP. Diffuse nodular lesion seen in this patient is an unusual finding for AEP and resembles bacterial infection