NUT Carcinoma of the Sublingual Gland.

NUT carcinoma (NC) is a recently described, rare and extremely aggressive cancer primarily located to supradiaphragmatic structures and affecting young individuals. NC is characterized by translocations involving the NUT gene on 15q14 with the most common translocation partner gene being BRD4 on 19p13, resulting in the t(15;19)(q14;p13) karyotype. NC is poorly differentiated and is likely to be overlooked and misdiagnosed as poorly differentiated squamous cell carcinoma (SCC) when immunohistochemical evaluation of NUT protein expression is omitted. Previously, NC has been found in the parotid and submandibular glands and we present the first case in the sublingual gland arising in a 40-year-old woman. We discuss the diagnostic considerations for poorly differentiated carcinomas of the salivary glands and advocate the inclusion of NUT immunohistochemistry in this setting. Not only does the NC diagnosis confer a grave prognosis when treated as SCC as illustrated by the present case, but is important for the inclusion of patients in ongoing clinical trials.