Solitary peripheral ciliated glandular papillomas of the lung: a report of 3 cases.

We report 3 cases of solitary papillomas located in peripheral regions of the lung that are extremely rare in the literature. The patients were 75-year-old and 72-year-old men and a 53-year-old woman. One patient complained of recurrent hemoptysis. The other 2 had no symptoms, but abnormal nodular shadows were revealed by chest radiographs during a health check. The maximum diameters of the tumors were 1.0, 1.4, and 1.1 cm, respectively. The 3 tumors gave almost the same histologic findings. Papillomatous fronds lined by a stratified columnar epithelium were seen in the lumens of peripheral bronchi, bronchioles, or alveoli. The stratified columnar epithelium consisted of ciliated, mucous, and basal cells. The neoplastic epithelium extended to the alveolar region and showed a similar appearance to bronchioloalveolar or papillary type adenocarcinomas. For differential diagnosis, it is noteworthy that endobronchiolar papillomatous fronds constantly exist and spreading along alveolar walls is limited in adjacent alveoli in peripheral papillomas. The presence of ciliated cells and basal cells is considered an important finding to suggest benign character of the lesion.