In previous studies, we have emphasized that reciprocal immunohistochemical profiles between keratin (K) 13 (loss) and K17 (emergence) are valuable for histopathological differential diagnosis of oral carcinoma in-situ (CIS) from epithelial dysplasia, which is challenging when only using hematoxylin and eosin (HE) stained sections1,2. The gene discussed is KRT17; the disease is in situ carcinoma.