TTF1 and AIDS dementia complex: Kim et al. [34] conducted a study with the aim of validating a variety of known immunohistochemical markers and study additional markers (i.e., Napsin A, CK5/6, Epithelial-related antigen (MOC-31), CD141, p27, CEA, TTF-1, p63, Cyclooxygenase 2 [COX-2], high-molecular-weight CK [HMWCK], and Rb protein) to accurately differentiate between ADC and SCC with obvious squamous or glandular differentiation in surgical resectates.