Cytologic negativity in the diagnosis of secondary pulmonary neoplasms

This retrospective study consisted of 55 patients with histologically confirmed metastatic cancer to the lung. Cytologic specimens were collected within 45 days before death. These included bronchial secretions, pleural effusions, and fine needle aspirations obtained randomly, either singly or in various combinations. The cytodiagnosis of cancer was made in 58% (32/55) of the patients. Originally, 34% (11/32) of these had been false-negative cases. Morphologic features associated with cytologic negativity in 23 patients included apparent failure to invade the respiratory air compartment in 57% (13/23) of the cases; when applicable, failure to induce a pleural effusion with neoplastic invasion of pleural tissues in 75% (6/8); peripheral distribution of the metastatic nodules to the outer third of the pulmonary parenchyma in 26% (6/23); and tumor size of less than 1.5 cm in 57% (13/23).