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.

The unique cytologic picture of oat cell carcinoma in effusions.

Characteristic and unique patterns of the tumor cell population in pleural effusions in oat cell carcinoma have been described in detail. This pattern is constituted by rows of tumor cells or cell layers forming "vertebrae like" figures and "onion like" formations. A distinct pattern of this kind was only found in oat cell carcinoma. A distinct "oat cell carcinoma pattern" was also found in one quarter of the patients in a series of oat cell cancer with cytologic analysis of sputum. This fact may be of importance for the accurate typing of small cell undifferentiated cancer in sputum and bronchial secretions. Identical formations were also found in a histologic series of oat cell cancer. The study indicates that in small cell carcinoma of the lung it is possible by cytologic analysis of positive effusions not only to make a diagnosis of carcinoma, but also to confirm the histologic type and, thus, the origin of the tumor.

Cytologic differential diagnosis of bronchiolo-alveolar carcinoma and bronchogenic adenocarcinoma.

In order to estimate the possibility of a cytologic differential diagnosis of bronchiolo-alveolar carcinoma and bronchogenic adenocarcinoma, 121 histologically proven cases of these two types of lung cancer were studied. Certain features of the tumor cells were used as differential diagnostic parameters. By means of these features it was possible to correctly type 90% of the bronchiolo-alveolar carcinomas and 72% of the bronchogenic adenocarcinomas. The most striking characteristics of bronchiolo-alveolar carcinoma was the uniformity of cells, the occurrence of such cells in tightly packed clusters, the absence of prominent nucleoli and also the scarcity of single tumor cells. Thus, it seems possible to make a correct cytologic differential diagnosis between these two types of lung tumors with high accuracy.