[A case of spindle cell (squamous) carcinoma (WHO) of the lung]

A 76-year-old man with spindle cell (squamous) carcinoma of the lung developed fatal respiratory failure after limited thoracic irradiation at a total dose of 18 Gy. He developed severe pulmonary toxicity, which presented as dry cough, dyspnea, and pulmonary infiltrates extending beyond the radiation field. Microscopically, a transitional form of squamous to spindle-shaped cells was observed in the primary tumor, located at right S8. Immunohistochemical examination showed positive staining of spindle cells for keratin, vimentin, and EMA, but not for desmin. These results indicate that the spindle cells had characteristics of squamous epithelial cells, and differed from carcinosarcoma. Distant metastatic lesions were composed of only the spindle cell component.