Papillary variant of low-grade mucoepidermoid carcinoma--an unusual bronchial neoplasm. A light microscopic, ultrastructural, and immunohistochemical study.

Abstract

The authors report an unusual bronchial papillary tumor found in the right lower lobe of a 89-year-old woman at the time of postmortem examination. The lesion was difficult to classify and did not fit well into any lung neoplasm category. Light and electron microscopic features were consistent with a papillary variant of low-grade mucoepidermoid carcinoma. Differential diagnoses mainly included the papillary bronchial mucous gland adenoma and the mixed epithelial-cell-type papilloma. Histogenetically, the tumor appeared to originate from the surface epithelium. Because the lesion showed features of low malignant potential, lobectomy would constitute an appropriate therapy whenever possible.