Figure 3

Pathological findings. (A) Computed tomography-guided needle biopsy reveals the tumor to have papillary stromal cores lined by pseudostratified ciliated or nonciliated columnar cells admixed with mucin-filled cells. The tumor cells show minimal atypia. (B) Cut surface of the resected specimen shows a whitish mucinous portion and a yellowish tumor cell portion in the center. The lesion is indicated by the arrow. (C) Histopathological image of the resected specimen shows papillomatous fronds lined by columnar epithelium and their extension toward the bronchiolar lumen. Surrounding alveoli are filled with mucus. (D) High magnification of the yellow box in C shows thick fibrovascular cores surrounded by goblet cells. The endobronchiolar surface of the tumor is covered mainly by ciliated epithelium with minimal atypia.