Histological findings of the present case. A high-grade carcinoma (black dotted line), which was different from the adenoid cystic carcinoma (AdCC) component (blue line), was seen in the central area of this tumor (A: whole mount H&E stain section). A focus of high-grade carcinoma (asterisk) was well demarcated in typical AdCC area and no gradual transition zone was seen (black dotted line) (B: H&E stain x20). Typical of AdCC showed a cribriform pattern (C: H&E stain x200). Solid subtype of AdCC was seen partly (arrow shows cribriform pattern within the solid subtype of AdCC.) (D: H&E stain x200). High-grade carcinoma showed solid and insular growth (E: H&E stain x200) with clear cytoplasm and marked nuclear atypia (F: H&E stain x400).