A Case of Spindle Cell Carcinoma on the Floor of the Mouth

Shinichi Taniguchi , Department of Oral and Maxillofacial Surgery, Ise Municipal Hospital, Ise-city, Mie-ken, Japan
Yasuo Kinoshita , Department of Oral and Maxillofacial Surgery, Ise Municipal Hospital, Ise-city, Mie-ken, Japan
Satoko Ito , Department of Oral and Maxillofacial Surgery, Ise Municipal Hospital, Ise-city, Mie-ken, Japan
[Introduction] Spindle cell carcinoma is characterized by the proliferation of polygonal cells, comprising mainly tumor cells, and is classified as a type of squamous cell carcinoma. The frequency of spindle cell carcinoma in the oral cavity is low, particularly on the floor of the mouth. We report a patient presenting with a spindle cell carcinoma on the floor of the mouth. [Case report] The patient was a 70-year-old male. He was aware of the tumor mass on the right floor of his mouth from approximately February 2013. The mass grew gradually and was observed by the neighboring village’s dentist in early January 2014. At the first visit to our hospital, the mass was observed as a well-circumscribed, soft, elastic, polypoid shape approximately 3.5 × 1.5 cm in diameter on the right floor of the mouth. No mucosal ulceration was seen, there was no interference with the movement of the tongue, or tenderness or swelling of the regional lymph nodes, and no bone resorption of the right mandible was evident in panoramic X-rays. Under a diagnosis of epulis, surgical removal of the tumor was performed under local anesthesia mid-January 2014. The mass was excised without signs of local infiltration and tumor margins were clear, histologically. The inner elastic surface was smooth and was assessed for enhancement-related parameters. Hematoxylin-eosin staining showed an invasive quality between epithelial layers with a mixture of heteromorphic original squamous epithelium and polymorphic spindle-shaped cells in a structured sarcoma-like arrangement. By immunostaining, the spindle-shaped cells were positive for vimentin, and the sarcoma-like section was weakly positive for AE1/AE3, CAM5.2, CK5/6, HHF35, desmin, and α-SMA. The results of staining for p63, CD34, and S-100 protein were negative. We received a histopathological diagnosis of spindle cell carcinoma and a whole-body CT scan revealed no metastases to other organs or lymph nodes. The lower right first molar, first premolar, and canine tooth were extracted under general anesthesia and resection of the floor of the mouth was performed under general anesthesia in early February under the diagnosis of spindle cell carcinoma (T2N0M0, STAGE II). The patient’s condition is currently good, with an uncomplicated postoperative course and no recurrence or metastasis to date. [Conclusion] We report a patient presenting with spindle cell carcinoma on the floor of the mouth.