Chemically induced pulmonary mucoepidermoid carcinoma in a female Wistar rat

A case of mucoepidermoid carcinoma, conventionally classified as an adenosquamous carcinoma, is described. The tumour bearing rat was exposed to a mixture of a pyrolized pitch condensate rich in polycyclic aromatic hydrocarbons and carbon black particles by inhalation for 10 months. The neoplasm was examined by conventional histopathologic procedures and by immunohistochemical detection of intermediate filaments. Morphologically, the tumour consisted of two components. The centre of the neoplasm was predominantly of adenocarcinomatous tissue and this was surrounded by keratinized squamous epithelium. The predominantly adenocarcinomatous component had a characteristic structural pattern consisting of one or a few layers of squamous epithelium covered by a continous layer of mature goblet cells. The flattered cells were recognizable as squamous cells on the light microscopic level only after immunohistochemical staining with cytokeratin antibodies. (Abstract truncated)