A 64-year-old woman is referred to the Pulmonary Service because of an abnormal finding on CT scan of the chest. Her symptoms include dyspnea on exertion, nonproductive cough, postnasal drip, and occasional wheeze; however, there were no fevers, chills, rest dyspnea, or fatigue. Five months prior to our initial evaluation, cough prompted a chest radiograph. An abnormal finding led to CT imaging. This showed multiple areas of ill-defined ground-glass attenuation (GGA). She is an ex-smoker (30 pack-years) who resides, along with two cats, in the Northeast with travel to England, New Mexico, and Arizona. She worked near the World Trade Center at the time of its collapse. Previously, she worked as an inpatient social worker with multiple negative purified protein derivative test results, last in 2002. Concurrent medical history includes osteoarthritis, hypertension, dyslipidemia, and glaucoma. Medications include losartan, hydrochlorothiazide, atorvastatin, rofecoxib, timolol drops, bimatoprost drops, and albuterol by metered-dose inhaler; she is allergic to penicillin. Her physical examination is notable for obesity with normal chest auscultation and percussion. There is no clubbing. Pulmonary function test findings are consistent with mild obstructive airways disease. The diffusing capacity is normal; however, there is desaturation with exercise. Symptoms persisted along with fleeting infiltrates on CT scan despite a 2-week course of clarithromycin, 250 mg/d. Laboratory data were as follows: WBC, 11.4 × 103/μL (normal differential); erythrocyte sedimentation rate, 35 mm/h; creatinine phosphokinase, 84 U/L; angiotensin-converting enzyme, 53 U/L; and C-reactive protein, 0.83 mg/dL. Serum fungal serology findings are negative. Initially refusing bronchoscopy, the patient underwent a left thoracotomy and superior segmentectomy of the left lower lobe for diagnostic purposes.