In immunohistochemistry, over-expression of HER-2/neu protein was identified as distinct membrane staining in most carcinoma cells in all our salivary duct carcinoma cases, while only four cases revealed an amplification of HER-2/neu gene by means of FISH analysis. Both amplified and non-amplified salivary duct carcinomas with strong immunohistochemical staining for HER-2/neu protein were associated with poor clinical outcome for the patients. Apparently, HER-2/neu protein over-expression could also be controlled by mechanisms other than gene amplification. In the group of salivary gland tumours other than salivary duct carcinoma, strong over-expression was detected only in three cases of carcinoma ex pleomorphic adenoma. Thus, over-expression of HER-2/neu protein is also a useful marker of malignant transformation in pleomorphic adenomas.

No abstract

We report four cases of parotid gland tumours composed predominantly of spindle-shaped myoepithelial cells and mature adipocytes. The central portion of one tumour showed extensive adipose differentiation, whereas in the peripheral parts there were small foci of ductal epithelium arranged in cords and tubules within an abundant myxoid stroma. The other cases were adipose spindle cell myoepitheliomas without an obvious glandular component. Under high-power examination, a transition between modified spindle-shaped myoepithelial cells and adipocytes was observed, and this was confirmed with immunohistochemistry. Ultrastructurally, the modified myoepithelial cells showed intracytoplasmic tonofilaments, bundles of actin microfilaments and lipid droplets. A possible pathogenesis is proposed of true metaplastic transformation of myoepithelial cells to adipocytes. This lesion is important to identify correctly, as inadequate surgery can lead to recurrence.