Clinically occult lung cancer with positive sputum cytology and primarily negative radiological findings.

Five patients with early clinically occult squamous cell carcinoma of the bronchus were reviewed with respect to previous sputum cytological examinations and clinical investigations. In one patient, selective bronchial washings demonstrated the site of the tumour and the patient was successfully operated. In the remaining four patients the interval between cytological diagnosis and radiological, bronchoscopical and/or histological demonstration of the tumour varied between 2 months and 9 years. It seems possible that the duration of bronchogenic carcinoma in situ may be of similar magnitude as that of carcinoma in situ of the cervix (10-15 years). The considerably higher frequency of early stromal invasion after semi-serial sectioning of carcinoma in situ of the bronchus compared with carcinoma in situ of the cervix is emphasized. The results stress that a diagnostic delay of several years is not acceptable, as the possibility of successful treatment will be greatly diminished in such cases.