Bronchial cytology in pleural mesothelioma. A report of 3 positive cases, including 1 diagnosed initially on bronchial brushings

OBJECTIVE: To evaluate retrospectively the value of bronchial aspiration cytology in patients with histologically proven pleural mesothelioma, reappraising positive smears in light of conventional microscopic features and, when feasible, immunocytochemical investigations. STUDY DESIGN: In 3 cases of mesothelioma with bronchial brushings positive for malignant cells, the cytologic features were correlated with the histologic findings. RESULTS: Salient microscopic features included scant to moderate cellularity arranged in micropapillary clusters, morular aggregates with scalloped borders and isolated malignant cells. Intercellular clear spaces or windows suggesting a brush border on cell membranes were also noted. In cases with available material, immunocytochemistry was positive for keratins, epithelial membrane antigen and calretinin and negative for carcinoembryonic antigen. All the cases were histologically confirmed epithelial mesotheliomas. CONCLUSION: In rare cases, pleural mesothelioma cells are shed within the airway lumina and can be detected in bronchoscopic cytology specimens. Cytologic features seem comparable to their analogues in pleural effusions. Although no single criterion appears diagnostic, their combined documentation could ensure correct interpretation, especially if supported by a limited immunocytochemical panel.