A 42-year-old married Saudi Arabian woman with three children was referred to the King Faisal Specialist Hospital and Research Centre because of fever with malaise and breathlessness of six weeks' duration.She had been treated at another hospital for one month where her symptoms gradually worsened until she was breathless on minimal exertion. There was neither orthopnea nor paroxysmal nocturnal dyspnea. She had a dry cough, occasionally producing small amounts of white sputum.Over the two weeks prior to admission, she had had intermittent episodes of stabbing, left-sided chest pain that was sometimes aggravated by deep breathing.At the other hospital, she had received courses of cefazolin sodium, ampicillin, and trimethoprim and sulfamethoxazole (Septra ® ). No other clinical information was available although she was not thought to have been on steroids or anti-tuberculous drugs. She was not taking the contraceptive pill.The patient had no significant medical history nor was there illness in her family or personal contacts. She thought that she had lost some weight but was not sure. Her bowel habits, micturition, and menses were normal. She was not aware of any allergies.On examination, the patient was yanosed and breathless. Her respiratory rate was 32/min at rest. She had a fever of 39.6°C. Height was 152 cm, weight 53 kg, and blood pressure 120/70 mmHg both lying and sitting. Her pulse was 110/min in sinus rhythm and neck veins were flat. The apical impulse was unremarkable. There was no parasternal heave. The pulmonary second sound was accentuated. There were no murmurs.The patient's trachea was central and chest movement was symmetrical and full. A few crackles that were not cleared by coughing were heard at the left base of the lung. There was neither a pleural nor a pericardial rub.Mouth and fauces were normal. The abdomen was soft and neither her liver nor her spleen could be felt. Her discs and retinae were normal. There were no neurological signs. There was no lymphadenopathy. The thyroid felt normal. Breast and vaginal examinations were normal. There was neither edema nor calf tenderness on examination of the legs.Initial investigations showed hemoglobin 12.2 g/dl; white cell count 8300/cmm; 35% lymphocytes; 52% polymorphonuclear leukocytes; 8% monocytes; 4% eosinophils; and platelets 210,000/cmm. The erythrocyte sedimentation rate was 60 mm in the first hour. Urinalysis showed a trace of protein with no sugar, no bilirubin, and no cells. Chest radiograph showed miliary mottling. A tuberculin skin test (5 units [TU]) showed 10 mm induration.Arterial blood gases, breathing room air with the patient sitting at rest were PO 2 44 mmHg; PCO 2 30 mmHg; pH 7.44; and HCO 3 20meq/1-