Solitary endobronchial papillomas with false impression of malignant transformation: report of two cases and review of the literature.

Solitary endobronchial papillomas (SEPs) are rare benign tumors of the lung, seldom transform to malignancy. This tumor had been reported occasionally manifest like carcinomas histologically. Herein we report 2 cases of SEPs; one is a squamous cell papilloma providing a false impression of interstitial micro-invasion. The other is a mixed squamous cell and glandular papilloma with massive lipid pneumonia gross appearance, and focally resembles adenocarcinoma with lepidic-like pattern on histological examination. A review of associated literatures was provided.