Moderately differentiated peripheral adenocarcinoma of the lung with cilia.

We report an extremely rare case in which cilia were identifiable on light microscopic examination in cells of a moderately differentiated peripheral adenocarcinoma in the lung. The cells were positive for cytokeratin 7, and the cilia were highlighted by epithelial membrane antigen staining. The prognostic significance of these extremely well-differentiated ciliated tumor cells will be known only with long-term follow-up of the patient and analysis of more such tumors.