No abstract available. Article truncated at 105 words. Clinical History: A 31-year-old previously healthy, immunocompetent, non-smoking female developed cough and was initially treated with broad spectrum antibiotics without improvement. Approximately 48 hours later, the patient presented to her physician with progressive shortness of breath and fever to 103°F. A chest radiograph was performed (Figure 1).Figure 1: Frontal chest radiograph shows extensive bilateral pulmonary opacities predominantly in the lower lobes with preserved lung volumes, normal mediastinal width, and no definite pleural effusion.The differential diagnostic considerations for the appearance on the chest radiograph include which of the following?1.Hydrostatic pulmonary edema2.Acute hypersensitivity pneumonitis3.Community-acquired pneumonia4.Opportunistic pulmonary infection5.All of the above