PAX8 and neoplasm: Immunohistochemically, the tumor cells were strongly and diffusely positive for CK and CK7, moderately positive for Dog-1, and negative for vimentin, P63, P40, napsin A, thyroid transcription factor 1, chromogranin A, CD56, synaptophysin, S-100, SRY-related HMG-box 10, and PAX8.