A 55-year-old woman visited our emergency department in September with two-day history of progressive dyspnea. The patient had never smoked and had no other previous medical history, but consumed half a bottle of alcohol daily. The patient had got a common cold one week prior, but her symptoms aggravated despite empirical treatment. After 5 days, she began to experience shortness of breath. Exertional dyspnea progressed to resting dyspnea the following day and at the emergency room, her initial peripheral oxygen saturation was 70%. Wet crackles and expiratory wheezing sounds were present in the whole lung field area. Evaluation of the patient's vital signs revealed a blood pressure of 140/80 mm Hg, body temperature of 36.6℃, pulse rate of 108 beats per minute, and respiration rate of 30 breaths per minute. Simple chest radiography showed the predominance of bilateral consolidation with ground glass opacity (GGO) in both lower lobes (
Figure 1A). Chest computed tomography indicated diffuse GGO with patchy consolidations in the whole lung field, but pleural effusion was not present (
Figure 2). Laboratory tests revealed a white cell count of 20,930/mm
3 (differential count: 91.5% neutrophils, 6.4% lymphocytes, and 0% eosinophil), hemoglobin concentration 12.7 g/dL, platelet count 366,000/mm
3, erythrocyte sedimentation rate 84 mm/hr, and C-reactive protein level 43.1 mg/dL. Analysis of arterial blood gases indicated a PaO
2 of 33.5 mm Hg, PaCO
2 26.1 mm Hg, HCO
3 19.7 mmol/L, and SaO
2 71.1% without acidosis. The patient's liver and renal function tests were within normal range. High-flow O
2 therapy and broad-spectrum antibiotics with oseltamivir (Tamiflu, Roche, Utley, NJ, USA) were started empirically, and bronchoscopy was performed immediately. Total cell counts of bronchoalveolar lavage (BAL) fluid were 240 cells/mm
3, including 75% neutrophils, 4% mononuclear cells, 1% eosinophil, and 20% macrophages. Cultures for common bacteria, acid-fast bacilli, and fungi were all negative. PCR for
Pneumocystis jirovecii, and
Mycobacterium tuberculosis were also negative. However, PCR of BAL fluid indicated the presence of rhinovirus, which was not detected following PCR of the nasopharyngeal specimen. Mycoplasma antibody and urinary pneumococcal antigen test were negative. Serologic test for venereal disease research laboratory test, hepatitis B surface antigen, hepatitis B, C antibodies, and human immunodeficiency virus, as well as for autoantibodies such as anti-nuclear antibody, rheumatoid factor, and anti-neutrophil cytoplasmic antibody were all negative. Clinical symptoms and infiltration on chest X-ray began to improve after five days (
Figure 1B), and the patient was discharged from hospital after three weeks.