Squamous cell carcinoma with rhabdoid features of the gingiva: a case report with unusual histology.

Squamous cell carcinoma (SCC) with rhabdoid features (SCCRF) is extremely rare in the oral cavity. We report herein a case of oral SCCRF. The patient was a 69-year-old Japanese woman who had been suffering from a mass in the right lower gingiva. Right hemi-mandibulectomy was performed. The gingival tumor was composed of pleomorphic, non-cohesive ovoid tumor cells with abundant cytoplasm and eccentric nuclei, which were positive for both pan-cytokeratin and vimentin. In another portion, moderately differentiated SCC and carcinoma in situ were also seen. A transition zone existed between the components. Finally, we diagnosed SCCRF. Four months after the operation, multiple bone metastases, lung and skin metastases and marked hypercalcemia were found. SCCRF, therefore, might be more aggressive than the usual type of oral SCC.