Detection of non-infectious conditions mimicking pneumonia in the intensive care setting: usefulness of bronchoalveolar fluid cytology

The present study investigated the usefulness of bronchoalveolar (BAL) fluid cytology in the identification of noninfectious pulmonary conditions in patients hospitalized in the intensive care unit (ICU) and suspected of pneumonia. A total of 182 BAL fluid samples obtained during a 27-month period from 130 ICU patients with suspected pneumonia were quantitatively cultured and investigated for opportunistic pathogens. Cytocentrifuged preparations stained with the May-Grunwald Giemsa and Perls's methods were reviewed. A non-infectious aetiology was considered when cultures yielded micro-organisms in quantities <10(3) colony-forming units (CFU) per mi, in the absence of any other pathogen and in conjunction with one or more of the following cytological findings: >20% haemosiderin macrophages, >10% lymphocytes, the presence of activated lymphocytes, plasma cells, >5% eosinophils, a preponderance of foamy macrophages, reactive type II pneumocytes or malignant cells. Patients' clinical records were reviewed to identify a clinical diagnosis for these episodes. In thirty-five (19.2%) BAL fluid samples from 26 patients, the cytological findings pointed to a non-infectious origin. An alternative diagnosis was ascertained in 20 of 26 patients. Diagnoses included: drug-induced pneumonitis (n = 7), aspiration of gastric contents (n = 2), pulmonary emboli (n = 3), adult respiratory distress syndrome (n = 4), lung contusion (n = 1), cardiogenic pulmonary oedema (n = 1), and carcinomatous lymphangitis (n = 2). The BAL fluid cytological findings were readily discernable and proved to be useful in the diagnostic work-up of samples obtained from ICU patients with suspected pneumonia. (C) 1999 Harcourt Publishers Ltd.