Ciliated muconodular papillary tumor: a solitary peripheral lung nodule in a teenage girl.

Papillary tumors of the peripheral lung containing ciliated cells and extracellular mucin include solitary peripheral ciliated glandular papilloma, ciliated muconodular papillary tumor, and well-differentiated papillary adenocarcinoma with cilia formation. We report the case of a 19-year-old woman who was a nonsmoker and presented with an incidental small peripheral lung nodule. The resection specimen showed a soft grayish nodule. Histologic examination further revealed a relatively circumscribed mucinous nodule featuring a tubulopapillary tumor composed of ciliated columnar cells and goblet cells, accompanied with abundant extracellular mucin. No lepidic growth pattern was evident. The tumor cells were immunoreactive for cytokeratin 7, thyroid transcription factor-1, and carcinoembryonic antigen, whereas p63 and cytokeratin 5/6 highlighted the presence of basal cells. Next-generation sequencing did not identify any genetic alterations in targeted regions and mutational hotspots of a panel of 22 genes commonly implicated in lung and colon cancers. Taken together, our case was most likely a ciliated muconodular papillary tumor.