Ciliated Muconodular Papillary Tumors of the Lung.

Ciliated muconodular papillary tumor is a rare tumor of the lung with 38 cases reported to date in the English literature. It is typically found incidentally in older adults (average age, 67 years) as a small, peripheral, ground glass opacity or nodule on computed tomography. Microscopically, the tumor is composed of a mixture of ciliated columnar, mucous, and basal cells in a variety of architectural patterns including glandular, papillary, lepidic, and micropapillary growth patterns. Recently, studies have shown the tumor has several associated gene alterations, supporting that the lesion is indeed neoplastic. The tumor seemingly follows an indolent clinical course, as there have been no reported recurrences or metastases. In this article, we review the clinical, radiographic, pathologic, and molecular findings of ciliated muconodular papillary tumors. Diagnostic pitfalls and the diagnostic considerations are discussed.