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) flui d cytology in the identification of noninfectious pulmonary conditions in p atients hospitalized in the intensive care unit (ICU) and suspected of pneu monia. A total of 182 BAL fluid samples obtained during a 27-month period f rom 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 n on-infectious aetiology was considered when cultures yielded micro-organism s 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 cy tological findings: >20% haemosiderin macrophages, >10% lymphocytes, the pr esence of activated lymphocytes, plasma cells, >5% eosinophils, a preponder ance 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 a scertained in 20 of 26 patients. Diagnoses included: drug-induced pneumonit is (n = 7), aspiration of gastric contents (n = 2), pulmonary emboli (n = 3 ), adult respiratory distress syndrome (n = 4), lung contusion (n = 1), car diogenic pulmonary oedema (n = 1), and carcinomatous lymphangitis (n = 2). The BAL fluid cytological findings were readily discernable and proved to b e useful in the diagnostic work-up of samples obtained from ICU patients wi th suspected pneumonia. (C) 1999 Harcourt Publishers Ltd.