[Clinicopathological features of bronchiolar adenoma versus mixed squamous cell and glandular papilloma: a...

Objective: To observe the clinicopathological features of bronchiolar adenoma (BA) and mixed squamous cell and glandular papilloma (MSGP). The relationship between them was also analyzed. Methods: Clinical data of eight patients with BA and four patients with MSGP diagnosed in China-Japan Friendship Hospital were collected from January 2018 to January 2020. Hematoxylin-eosin staining and immunohistochemical staining (EnVision method) were used to compare their histopathological characteristics. The hotspots regions of cancer-associated driver genes in lung cancer, using real-time quantitative PCR, were detected in all the cases and the literatures were reviewed. Results: The clinical and imaging manifestations of BA and MSGP were analogous. Histologically they had a two-layer structure including bronchial or bronchiolar-type epithelium and a continuous layer of basal cells,similar to bronchial/bronchiole mucosae. P16 protein was highly expressed in 7/8 of BA and 1/4 of MSGP. Mutations of cancer-associated genes were detected in 4/8 of BA, but none in MSGP. Conclusions: BA and MSGP, derived from different parts of the respiratory tract in the lungs, are rare and benign. Their morphological features overlapped with each other, and some cases are accompanied by genetic changes. It is necessary to pay attention to the differential diagnosis between them and lung adenocarcinoma, especially during the intraoperative diagnosis; and be alert to the potentially malignant components in the tumor or combined cancers.