Adenocarcinoma Comprising Sarcomatoid Carcinoma of the Lung Proliferating Rapidly in the Right Main Bronchus

An 82-year-old male was referred to hospital with cough. A chest computed tomography scan revealed atelectasis of right upper lobe and obstruction of the upper lobe bronchus. We conducted a transbronchial biopsy, but could not make a diagnosis. The mass proliferated rapidly, resulting in complete obstruction of the right main bronchus. Since the patient experienced severe respiratory failure, we performed right upper sleeve lobectomy in an emergency. The findings of histopathological examination revealed adenocarcinoma. However, several sarcomatoid carcinoma cells with a few adenocarcinoma cells were observed only in an intra-bronchial development part.