Cytokeratin profile in mucoepidermoid carcinoma is not related to its histological grading of malignancy.

The objective of this experiment was to determine the relationship between the expression of cytokeratins (CKs) and histologic grading in MEC. Eleven cases of MEC were selected and graded as low, intermediate and high-grade tumors. The expression of CKs 7, 8, 10, 13 and 14 was assessed immunohistochemically using streptavidin-biotin complex method. The results showed that the studied CKs were expressed in most cases of MEC, independently of histologic grading. Nonetheless, low-grade tumors demonstrated intense staining of CK 7 and 8; additionally, CK 10 and 13 were more pronounced in this grade. The immunoexpression was variable according to cellular type and organization pattern of the tumor. Mucous cells were positive for CK 7 and 8; epidermoid cells were stained for CK 10, 13 and 14; CK 7, 8, 10 and 14 were observed in intermediate cells, and CK 7 was occasionally seen in clear cells. Cystic structures and duct-like elements in MEC were positive for CK 7 and 8, whereas solid nests showed positivity for all CKs. These results suggest that expression profile of these proteins does not reflect the biological behavior of MCE, however, it guides the detection of cellular types and differential diagnosis from other salivary gland tumors.