Clinicopathological significance of NUT rearrangements in poorly differentiated malignant tumors of the upper respiratory tract.

Nuclear protein in testis (NUT) midline carcinoma (NMC) is a highly malignant carcinoma originating from the midline of the body. This study investigated the clinicopathological significance of NUT rearrangements in poorly differentiated malignant tumors (PDMTs) of the upper-respiratory tract (URT) in China. The clinical and pathological features of 155 PDMTs of the URT were reviewed. Epstein-Barr virus (EBV)-encoded RNA and NUT were investigated by in situ hybridization and immunohistochemistry (IHC), respectively. NUT-positive cases were examined by fluorescence in situ hybridization (FISH) and immunohistochemical staining with a set of cytokeratins (CKs) and neuroendocrine markers. One case was observed by transmission electron microscopy. Four cases of poorly differentiated squamous cell carcinomas and sinonasal undifferentiated carcinomas were diffuse positive for NUT by IHC and also stained for antibodies to CKs and P63 but were negative for neuroendocrine markers. Only 2 of these 4 cases showed rea...