Basaloid-squamous cell carcinoma of the oral mucosa: report of two cases and study of the proliferative activity.

Two cases of basaloid-squamous cell carcinoma (BSC) of the oral mucosa are described. The first case occurred at the floor of the mouth in a 58-year-old man, and the second case occurred at the mandibular gingiva in a 79-year-old woman. The laboratory data of the first case showed a positive response to hepatitis C virus antibody. In the first case, the tumor mass measured 4 x 4 cm in size, and was located at the lingual side of the median mandible beside the sublingual gland. In the second case, the tumor mass measured 25 x 15 mm in size, and was located in the alveolar mucosa of the right mandible. Histologically, both tumors showed a neoplastic epithelium arranged in a solid pattern with evidence of peripheral palisading, central necrosis, and some squamous differentiation. The proliferative activities of the BSC were compared with conventional squamous cell carcinomas (SCC) in the oral floor and gingiva, respectively, by employing a sensitive argyrophilic nuclear organizer region (AgNOR) staining method. The number of AgNOR per nucleus of the BSC was higher than that of any other SCC cases. The results support the opinion that BSC of the oral mucosa has a worse prognosis than conventional SCC.