Cytological findings of mixed squamous cell and glandular papilloma in the lung.

Pulmonary mixed squamous cell and glandular papilloma is an extremely rare neoplasm. This is the first cytological report of such a rare neoplasm. A 59-year-old Japanese man was admitted to the hospital complaining of a persistent cough and bloody sputum. A bronchial endoscopic examination revealed an endobronchial polypoid tumor. Upon bronchial brush cytology by Papanicolaou stain, squamous dysplasia showing mild atypia was suspected. The smears showed moderate cellularity with singly scattered cells or loose clusters of cells, consisting of squamous cells and a few columnar cells. Nuclei of the squamous cells showed mild atypia, but there was no nuclear atypia of the columnar cells. Upon intraoperative pathological examination by frozen section, pulmonary mixed squamous cell and glandular papilloma was suspected. Intraoperative imprint cytology by Ultrafast Papanicolaou stain showed a few differences in comparison with bronchial brush cytology, which were thought to be due to differences in obtaining cytological specimens or the steps prior to the staining. The patient underwent a segmentectomy of the left lung. Histopathological diagnosis confirmed a mixed squamous cell and glandular papilloma. The postoperative course has been uneventful for 5 years after surgery. It was thought that cytology was diagnostically inadequate on its own in the present case. However, mixed squamous cell and glandular papilloma must be considered as another type of pulmonary tumor in cytological preparations, especially in a case showing endobronchial papillary growth by bronchoscopy.