ABSTRACT
I. Introduction The clinical presentation and diagnosis of Pneumocystis pneumonia (PcP) in human immunodeficiency virus (HIV)–infected patients can be challenging for several reasons. First, PcP is the HIV-identifying diagnosis in a significant proportion of patients, and clinicians must maintain a high index of suspicion in evaluating a patient who has no knownHIV diagnosis but whose clinical and radiographic presentation is compatible with PcP. Although PcP has a characteristic clinical and radiographic presentation, the extent to which the ‘‘classical’’ presentation is seen depends on several factors, including the use of Pneumocystis prophylaxis. Furthermore, the clinical and radiographic presentation of PcP overlaps that of other HIV-associated pulmonary diseases. Occasionally, the chest radiograph-which is the cornerstone of the evaluation of suspected PcP-will be normal, and additional tests, such as chest high-resolution computed tomography (HRCT) or pulmonary function tests (PFTs), may be indicated. PcP-associated acute respiratory failure requiring mechanical ventilation has a significant mortality; prompt diagnosis and initiation of treatment are therefore critical. Finally, there is no universally agreed on diagnostic algorithm for suspected PcP, and institutions report different degrees of success with sputum induction and bronchoscopy with bronchoalveolar lavage (BAL).
