Nuclear protein in testis midline carcinomas: a lethal and underrecognized entity.

A 54-year-old woman presented with a nasal mass. Biopsy demonstrated undifferentiated tumor cells with extensive apoptosis and necrosis. Chromosome analysis identified a 46,XX,t(15;19)(q13;p13.1) pattern. Nuclear protein in testis (NUT) immunohistochemistry and fluorescence in situ hybridization confirmed NUT rearrangement. A Ewing sarcoma-based chemotherapy regimen and concurrent irradiation obtained a dramatic response; however, the patient died of her disease less than 7 months after initial diagnosis. NUT midline carcinomas are rare, aggressive tumors defined by rearrangement of the NUT gene on 15q14. A solitary translocation involving 15q14 is usually the sole chromosomal abnormality in these carcinomas. Immunohistochemical expression of NUT in the nuclei of non-germ cell tumors is theoretically diagnostic. More widespread use of a newly available NUT immunohistochemical stain will facilitate the diagnosis of NUT rearranged carcinomas. From the growing numbers of identified cases, effective targeted therapies can be developed.