Immunohistochemical expression of cytokeratins in human salivary gland acinic cell carcinomas

Abstract

To compare the expression of cytokeratins (CKs) in the solid, microcystic, follicular, and papillary-cystic subtypes of salivary gland acinic cell carcinoma (AcCC) in order to characterize the cell origin. The expression of CK7, CK14, CK19, CK20, and alpha-smooth muscle actin (α-SMA) in 18 cases of AcCC was assessed with the use of immunohistochemical staining. Ten normal salivary glands were used as controls. The expression of CKs in AcCCs varied according to their growth patterns. CK7 showed strong and diffuse positive staining in the microcystic, follicular, and papillary-cystic subtypes, whereas staining was weakly positive or negative in the solid subtype. CK14 expression was negative in almost all AcCCs. Expression of CK19 was observed in the microcystic, follicular, and papillary-cystic subtypes, but was minimally observed in the solid subtype. No cells positive for CK20 or α-SMA were found in any AcCCs. We demonstrated that the microcystic, follicular and papillary-cystic subtypes of AcCC exhibit features ofductal luminal cells with expression of CK7 and CK19, suggesting their ductal origination. By contrast, the solidsubtype might originate from different cells with no ductal CK expression.