Abstract

Percutaneous needle biopsies were performed on 683 patients with solitary pulmonary nodules during 1976-84. A cytological diagnosis of malignancy was made from the first biopsy in 473 patients (69%). A second biopsy was performed in 43 patients, a diagnosis of malignancy being made in a further 16 cases (37%). Histological material was available for comparison with cytological findings in 203 patients. Cytological examination was reliable in the diagnosis of malignancy with a high yield (75%) and low false positive rate (1.5%). Specific benign lesions were correctly diagnosed in 10 patients (1.5%). There was a false negative rate for the diagnosis of malignancy of 18% for the patients with a subsequent histological diagnosis. This compares with a false negative rate of 9% overall; the true rate probably lies between these figures. These results imply that a cytology report indicating no evidence of malignancy, but not diagnostic of a specific benign condition, does not reliably exclude a malignant lesion. In this series cytological typing was not accurate at predicting the cell type determined by histological examination (61% agreement) and was not able to discriminate between small cell and non-small cell lung cancer.