Abstract
Background : Mucoepidermoid carcinoma of the bronchus is a rare malignant tumor. We report a case of mucoepidermoid carcinoma which could be diagnosed by liquid based cytology (LBC) of bronchial brushings.
Case : A 20-year-old man with an abnormal opacity in the right lung hilum was diagnosed as having bronchiectasis. A mass lesion was present in the right bronchial lumen, and LBC of bronchial brushings was performed. The tumor cluster was arranged in sheets or three-dimensional gland-like structures. The tumor cells showed an elevated N/C ratio and slight irregularity of the nuclear shapes, and included mucous cells and squamous cells. On immunocytochemistry, the tumor cells showing squamous differentiation were p63-positive and the mucous cells were human gastric mucin-positive. The tumor was diagnosed as a mucoepidermoid carcinoma. Histologically, the tumor consisted of a solid tumor with large and small cystic spaces in fibrous connective tissue a fibrous stroma. The tumor cells consisted of mucous and squamous and intermediate cells. The Ki-67 labeling index of the tumor cells was under 1% on immunohistochemistry. We finally diagnosed the tumor as low-grade mucoepidermoid carcinoma.
Conclusions : LBC revealed three-dimensional clusters reflecting tissue structures, as compared to conventional smears. Therefore, these findings should be borne in mind when using LBC for diagnosis.
