Abstract
Background : Thymic papillary adenocarcinoma is a rare carcinoma associated with a typical papillary growth pattern. We report a case of papillary adenocarcinoma of the thymus with cyst formation.
Case : A 68-year-old woman admitted for an abnormal right lung field shadow in chest X-ray imaging. Chest computed tomography showed an anterior mediastinal cystic lesion 5 cm in diameter and a tumor nodule 1 cm in diameter within the cyst. Cystic fluid cytology showed several small papillary cell clusters with an inflammatory background. Neoplastic cluster cells showed mild atypia featuring small nuclei, slightly increased chromatin, and small nucleoli. The histopathological diagnosis was papillary adenocarcinoma containing a type A thymoma component associated with cyst formation.
Conclusion : Papillary adenocarcinoma should be suspected when an aspiration cytology specimen from a cystic lesion in the mediastinum contains papillary cell clusters.
