Physical examination revealed an elderly white woman breathing comfortably at rest. She was afebrile. Room air oxygen saturation was 84% and increased to 96% with 2 L of oxygen. Chest examination revealed bibasilar dry crackles. Heart sounds were regular and without murmurs or gallops. The abdomen was soft and nontender, with no evidence of organomegaly. Neurologic examination revealed no focal deficits. Laboratory tests revealed a WBC count of 1,900/μL with 70% neutrophils; 17% lymphocytes; 9% monocytes; 3% eosinophils; hemoglobin, 10.2 g/dL; and platelet count, 202,000/μL. B-natriuretic peptide was 53 pg/mL. Chest radiograph showed low lung volumes, bronchovascular crowding, and basilar subsegmental atelectasis. Echocardiography demonstrated normal ejection fraction and normal valvular structures. Pulmonary function tests revealed moderate restriction (FVC, 2.00 L [63% predicted] and FEV1, 1.48 L [59% predicted]) and a diffusion capacity of 8.58 mL/min/mm Hg (33% predicted). Prior spirometry results in March 2003 had been normal: FVC, 3.11 L (97% predicted), and FEV1, 2.38 L (93% predicted). Blood and urine cultures were sent. She was treated with IV ceftazidime, azithromycin, and vancomycin for 4 days with minimal clinical improvement and remained hypoxic. All culture results were negative. A CT scan of the chest demonstrated ground-glass opacities (Fig 1
, top, A). Bronchoscopy with BAL and transbronchial biopsies was performed. Fluid was sent for bacterial, viral, fungal, acid-fast bacilli, and Legionella cultures, all of which came back negative. Transbronchial biopsies revealed nonspecific inflammation. However the BAL differential was highly abnormal, revealing 33% macrophages and 65% lymphocytes (Fig 2
). The high lymphocyte percentage was suggestive of a hypersensitivity-like pneumonitis. Flow cytometric analysis of the BAL lymphocyte population6 revealed 99% of the lymphocytes were CD3+ T-cells, with a CD4:CD8 ratio 0.61 (normal, 1.7 ± 1.0). Parenteral antibiotics were stopped, and the patient was discharged receiving oral cephalexin after a 7-day hospital stay. The patient did not receive corticosteroids during her hospital stay, nor was she discharged receiving on them. Prior to discharge, a home oxygen evaluation showed a resting room air blood gas pH of 7.46; Pco2, 37 mm Hg, Po2, 66 mm Hg, and oxygen saturation of 91%. She required 1 L of oxygen with exercise.