A Case of Pulmonary Mucoepidermoid Carcinoma with Cilia That Was Difficult to Differentiate from Ciliated Muconodular Papillary Tumor

• Published in: The Journal of the Japan Society for Respiratory Endoscopy Vol. 42; no. 5; pp. 392 - 397
• Main Authors: Miyahara, Takashige, Akahane, Junpei, Muramoto, Miho, Yamanaka, Miwa, Uehara, Kai, Uehara, Tsuyoshi, Yamada, Kyoko, Yokozeki, Mari
• Format: Journal Article
• Language: Japanese
• Published: The Japan Society for Respiratory Endoscopy 25.09.2020
• Subjects: Cilia; Ciliated muconodular papillary tumor; Immunostaining; MAML2 gene; Pulmonary mucoepidermoid carcinoma
• ISSN: 0287-2137; 2186-0149
• DOI: 10.18907/jjsre.42.5_392

Background. The presence of ciliated cells is likely to be taken as evidence of a benign tumor. Case. The patient was a 33-year-old man who underwent chest CT during health screening in our hospital. Chest CT demonstrated a nodular shadow of 9 mm in diameter in the right upper lobe. Although the tumor size has not changed, we performed bronchoscopy 15 months after the identification of the shadow on chest CT. The histopathological findings showed bronchoepithelial cells with cilia and a papillary proliferation of basal cells. Ciliated muconodular papillary tumor (CMPT) was suspected, and after a check-up 33 months later, right S3 segmentectomy was performed, supported by video-associated thoracoscopy. Due to the difficulty in differentiating between CMPT and mucoepidermoid carcinoma (MEC) in the immunohistochemical staining of surgical tissues, a genetic analysis of the MEC specimen was performed to detect MAML2, which yielded a positive result. We diagnosed the patient with MEC. Conclusion. In addition to immunostaining, a genetic analysis is useful for the diagnosis of uncommon variants, which can be difficult to diagnose.