Study of minor salivary gland mucoepidermoid carcinoma differentiation based on immunohistochemical expression of cytokeratins, vimentin and muscle-specific actin.

The expression of cytokeratins (CKs) 7,8,10,13,14,18,19, vimentin and muscle-specific actin (MSA) was investigated in 17 mucoepidermoid carcinomas (MEC) by the streptavidin-biotin technique. The results revealed that CKs 7, 8 and 18 were positive for intermediate, luminal columnar and mucous cells. For epidermoid cells, the expression was heterogeneous and discrete. The reaction with CK19 was similar to that seen for the above CKs, except for the fact that mucous cells were negative. CK 14 was preferentially expressed in the intermediate cells localised in basal, parabasal and epidermoid cells. CK13 was localised in intermediate, epidermoid and luminal columnar cells. In stratified epithelium, CK13 was expressed in intermediate cells and negative in basal cells. These findings were more expressive in cystic areas of the tumours. CK10 was negative for all the cases studied. MSA was positive only in stromal elements, and only two cases of CME were heterogeneously positive for vimentin. The result obtained showed that the immunoprofile of MEC, for the studied antigens, is similar to that exhibited by the excretory duct of normal salivary glands.