A case of spindle cell carcinoma of the oral cavity in a 78-year-old woman is reported together with the immunohistochemical and electron microscopic findings. She had a peduculated tumor mass measuring 30 X 45 mm in the lingual mucosa on the right side of her mandible. The tumor was diagnosed as spindle cell carcinoma by histopathological examination of biopsy specimen, and a segmental resection of the mandible with the tumor mass was performed.
Histologically, the tumor contained two kinds of structural patterns: well-differentiated squamous cell carcinoma, and a sarcomatous appearance of diffusely proliferating spindle-shaped tumor cells with a high frequency of mitotic figures. The sarcomatous areas were closely associated with the areas of squamous cell carcimona. Immunohistochemically, the tumor cells of sarcomatous areas were positive for keratin, epithelial membrane antigen (EMA) and vimentin, and negative for desmin and actin. Electron microscopy revealed that some of the spindle-shaped tumor cells were connected with desmosomes and a few of them contained tonofilaments. Three months later, the patient had a local recurrence. Radiotherapy was performed, but it failed to control the malignant growth.
The patient's general condition deteriorated gradually, and she died seven months after surgery.
