Pulmonary infiltrates in an elderly man

An 80-year-old man presented with subjective fever, chronic cough occasionally producing scant yellow sputum, retrosternal pleuritic pain, and dyspnea on walking one block. Since symptom onset three months earlier, he had lost 20 pounds; he had had two loose stools a day, fatigue, malaise, and anorexia but not hemoptysis, nausea, vomiting, hematemesis, hematochezia, or melena. He denied paroxysmal nocturnal dyspnea or orthopnea. As far as could be ascertained, he not recently been exposed to tuberculosis or any other infectious disease. He had previously been seen at another clinic and had completed a 10-day trial of erythromycin (500 mg p.o. q12 h) without apparent change in symptoms.