A Typical Atypical Pneumonia

20 A55-year-old white man from eastern Ontario with a past medical history of class IV angina and no previous significant infectious disease history presented to the emergency room with a five-day history of left-sided, pleuritic chest pain, dyspnea and cough productive of clear sputum. He had no hemoptysis, chills or previous exposure to tuberculosis, but had lost 9 kg in the previous month. He had not travelled recently, was not exposed to any unusual animals and had no pets. He smoked 40 packs of cigarettes/year. His medications were acetylsalicylic acid, nitroglycerine and metoprolol. On admission, he was febrile and hypoxic (oxygen pressure of 69 breathing room air), yet his chest was clear to auscultation. His white blood cell count was 10.5 × 109/L, with a normal differential, and the sedimentation rate was 215 mm/h. Chest radiography showed a lateral, diamondshaped area of opacity in the left mid-lung zone, abutting the chest wall (Figure 1). A D-dimer assay was negative and a ventilation perfusion scan was interpreted as being of low probability for pulmonary embolism. The patient was treated with intravenous erythromycin and cefuroxime, but remained both febrile and hypoxic. HIV serology and sputum cultures were negative. A biopsy of the lesion was performed.