[A case of lung cancer with Mallory bodies]

This paper is a report of a large cell carcinoma (solid carcinoma with mucus formation-WHO) which developed in the right upper lobe of a 71-year-old woman and in which cytoplasmic Mallory body-like inclusions (MBL) similar to Mallory bodies (MB) often found in alcoholic liver disease and hepatocellular carcinoma were noted in the tumor cells. MBL was an eosinophilic massive or reticular hyalin, and showed staining properties similar to those of MB in general stainings. Electron microscopically, it was made up mainly of a fine granular amorphous substance with high electron density and was not surrounded by a membrane. A part of the margin was in close contact with filaments approximately 10 nm in diameter, with tonofibril-like structures around it, which suggested a relationship with cytokeratin. On immunoperoxidase staining using a couple of cytokeratin antibodies, definitely positive findings were not obtained with MBL themselves. MBL of this case basically has the same character as that of MBL which appears in fibrous lesions in the lung and MB in liver disease. It was concluded that it is necessary to preoperatively distinguish this entity cytologically or histologically from pulmonary metastasis of hepatocellular carcinoma.