Clear cell carcinoma of minor salivary glands.

Two cases of carcinoma of the minor salivary glands are presented in which most cells had clear cytoplasm. Both patients had clinical histories in excess of 10 years and, in the one case with adequate follow-up, no recurrence had occurred after a further 11 years. Both tumours were locally invasive. The clear cells contained small amounts of glycogen, but no intracytoplasmic mucin. Immunohistochemical and ultrastructural studies showed epithelial features, with no evidence of myoepithelial differentiation. These tumours were very similar to the small number of previously reported cases, which were all considered to be low-grade carcinomas. Amongst the differential diagnoses, the most important is metastatic clear cell carcinoma of the kidney and this can only be confidently excluded clinically or by the use of imaging techniques. In summary, we consider intraoral clear cell carcinoma to be a distinct tumour of low malignant potential.