Idiopathic acute eosinophilic pneumonia in a 14-month-old girl
A previously healthy 14-month-old girl was transferred to our hospital because of fever, dry cough and progressive dyspnea for 1 day. On physical examination, she exhibited marked respiratory distress and marked chest wall retractions. Her temperature was 38.6℃, blood pressure was 110/60 mmHg, pulse rate was 180/min, and respiratory rate was 75/min. Her breathing sounds were decreased, and crackles and wheezing were audible in both lungs but without cardiac murmurs.\nComplete blood cell counts revealed the following: white blood cells, 6,900/uL (neutrophils, 76%; lymphocytes, 19.3%; monocytes, 4.3%; and eosinophils, 0.1%); hemoglobin, 10.7 g/dL; and platelets, 277,000/µL. After 5 L/min of oxygen was applied through a nasal prong, arterial blood gas analysis showed the following: pH, 7.39; PaCO2, 43.5 mmHg; PaO2, 73.7 mmHg; HCO3, 23.9 mEq/L; base excess, -1.6 mEq/L; and oxygen saturation, 94.1%. Other blood biochemical tests were normal. Chest radiography showed patchy consolidations in the right lower lung, bilateral peribronchial infiltrations and pneumothorax in the left upper lung (). High-resolution computed tomography (CT) of the chest showed multifocal ground-glass opacity, increased interstitial lung markings, parenchymal emphysema and pneumothorax ().\nFurther workup results were negative for rheumatoid factors, antinuclear antibody, antineutrophil cytoplasmic antibody and fluorescent antinuclear antibody. Serum humoral antibody levels were normal (immunoglobulin [Ig] G, 738.0 mg/dL; IgM, 357.0 mg/dL; IgA, 42.0 mg/dL; and IgE, 11.3 IU/mL). T cell subsets were also within normal limits (lymphocytes, 4,643 /µL; CD4+T cells, 1,518/µL; CD8+T cells, 931/µL; and CD4+/CD8+ T cells, 1.63) and the serum levels of C3, C4, and CH50 were 124 mg/dL, 19.1 mg/dL, and 38.0 U/mL, respectively.\nDifferential diagnoses, including severe community-acquired pneumonia, acute interstitial pneumonia (AIP), aspiration pneumonia and acute hypersensitivity pneumonitis, were excluded. Blood and sputum cultures for bacteria and fungi were negative. Antibodies for Mycoplasma pneumoniae, Chlamydia trachomatis, Rickettsia tsutsugamushi and Ebstein-Barr virus were negative. Parasitic infestations were excluded by the negative results of tests for specific antibodies for Cysticercus, Sparganum, Paragonimus, and Clonorchis. No respiratory viruses except human bocavirus (HBoV) were detected in the polymerase chain reaction (PCR) of her nasopharyngeal aspirates. Despite broad spectrum antibiotics and supportive care, the patient continued to worsen over the next 48 hours, requiring a positive end-expiratory pressure of 10 cmH2O and a 75% fraction of inspired oxygen to maintain an oxygen saturation of 90%.\nA lung biopsy was performed on the 5th hospital day and demonstrated marked infiltration of eosinophils to alveolar spaces, peribronchiolar tissues and interstitium (). There was no evidence of viral (cytomegalovirus, Epstein-Barr virus, and human immunodeficiency virus), bacterial (Chlamydia trachomatis, Mycoplasma pneumoniae, and Mycobacterium tuberculosis), or fungal infection (Pneumocystis jiroveci) from the lung biopsy specimens.\nIntravenous corticosteroid pulse therapy (methylprednisolone 30 mg/kg) was begun. The patient's pulmonary status rapidly improved, requiring less ventilator support and showing clearing of infiltrates on chest X-rays (). Three days after the initiation of steroid therapy, the patient was successfully extubated. She was eventually discharged on the 18th day in good condition with a course of oral prednisone therapy tapered for a further 14 days.