Abstract
Carcinoma cuniculatum (CC) has been regarded as a well differentiated subtype of oral squamous cell carcinoma (SCC) that is characterized by keratin cores and keratin-filled crypts, but lacking obvious cytological malignancy. There have been relatively few case reports of oral CC, and descriptions of the long-term prognosis are scarce. In addition, the process of change from CC to conventional SCC is still poorly understood. In 1983, an 80-year-old woman admitted for a white spot underwent an excision biopsy, and CC was diagnosed. This lesion then recurred in 1993, with the same diagnosis, but it changed into conventional SCC when it recurred in 1994. Tissue materials from the three surgical treatments were examined with hematoxylin and eosin stain as well as with immunohistochemical stains for Ki-67 and for p53 and p63 gene products (P53, P63). While expressions of P53 protein and Ki-67 became stronger with every recurrence, the opposite tendency was obtained for P63 expression. This is the first report to describe a case of long-term follow-up of CC in which the expression modes of oncogene products were analyzed.
