Cases positive for NUT immunohistochemistry and negative for EBER in situ hybridization were submitted for fluorescent in situ hybridization (FISH) for rearrangements in both BRD4 and NUT genes, and immunohistochemical staining for a set of cytokeratins (AE1/AE3, CK7, CK8), p63,and neuroendocrine markers (NSE, Syn, CgA, S-100 protein, CD56). 