Cytologic diagnosis of occult small-cell undifferentiated carcinoma of the lung.

: Small-cell undifferentiated carcinoma of the lung is usually metastatic and/or locally advanced at diagnosis. We describe an occult tumor that cytologic techniques diagnosed in a minimally symptomatic, high-risk individual. Despite the absence of radiologic or histopathologic confirmation, bronchoscopically directed cytologic specimens localized the lesion. A tiny, apparently stage I, small-cell undifferentiated carcinoma was successfully resected.