Abstract
BACKGROUND: Sclerosing pneumocytoma is a rare lung tumor that is usually recognized as a solitary nodule in the lung. Surgical removal is recommended; however, its clinical diagnosis is still an issue because it is difficult to differentiate from lung adenocarcinomas using a tiny sample obtained from biopsy. CASE PRESENTATION: We report a case of pulmonary sclerosing pneumocytoma located in the upper lobe of the right lung of a 34-year-old woman, which was diagnosed before surgery by endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA). A 3-cm irregular mass was detected by chest X-ray without any symptoms. She was referred to our hospital after being followed for 10 years in her previous clinic. During this follow-up period, the tumor had grown to 5 cm. We performed the EBUS-TBNA for the diagnosis. The histological findings obtained by EBUS-TBNA consisted of alveolar type 2-like cells that were positive for napsin A and round cells that were positive for vimentin. Based on these immunostaining results, we successfully diagnosed sclerosing pneumocytoma before surgery. Right upper lobectomy was performed, and the pathological diagnosis of the surgical specimen was also confirmed as sclerosing pneumocytoma. CONCLUSIONS: We herein report a case of sclerosing pneumocytoma, which was clinically diagnosed by EBUS-TBNA and resected surgically.