Tuberculosis is a common cause of cavitating pneumonia in Singapore. In patients with the human immunodeficiency virus (HIV), cavitary pneumonias mimicking tuberculosis can mislead the clinician, delaying diagnosis, resulting in increased morbidity. We describe a HIV seropositive patient with cavitating pneumonia in whom the diagnosis of Pneumocystis carinii pneumonia (PCP) was ultimately established only on bronchoscopy.
PIP: In February 1991, a 30-year old single, Chinese male, who had not has sexual intercourse with another man but did have it with a woman while in another country 12 months earlier, sought medical care at Tan Tock Seng Hospital in Singapore. He had a productive cough for 3 months, lost 5 kg over 4 months, and had been gasping for breath for 3 days. Upon admission, he had a low grade fever and breathed very rapidly while resting. The apical segment of the right lower lobe of the lung had a 3 x 2 cm cavity which was filling with exudate. A sputum smear did not indicate acid fast bacilli in 2 of 3 samples and blood cultures did not yield aerobic or anaerobic bacteria. The Western blot test revealed HIV antibodies. The absolute CD4 lymphocyte count stood at 80/cu mm compared with more than 500/cm mm in healthy individuals. Physicians used a bronchoscope to do bronchoalveolar lavage (BAL) and transbronchial lung biopsy (TBLB), both of which disclosed cysts of Pneumocystis carinii. Treatment first consisted of trimethoprim/sulfamethoxazole for 7 days and antituberculosis chemotherapy for 2 weeks until the physicians realized he had Pneumocystis carinii. They switched the treatment to iv pentamidine isethionate because he still had a fever after 7 days. This treatment was successful. Physicians then administered Zidovudine (AZT) and aerosolized pentamidine each month. As of mid-1992 he was still healthy. In addition to the BAL/TBLB results indicating Pneumocystis carinii and excluding tuberculosis, other features excluding tuberculosis were a Mantoux reading of O, absence of hilar and/or mediastinal lymphadenopathy, response to pentamidine isethionate, and sputum and blood cultures that did not indicate Mycobacterium species.