[Clinicopathological analysis of nuclear protein in testis midline carcinoma]

Objective: To investigate the clinicopathological features, immunophenotype and prognosis of nuclear protein in testis (NUT) midline carcinoma. Methods: Twenty-four resection cases of NUT midline carcinoma diagnosed at the Department of Pathology, Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China from January 2018 to September 2022, were collected, and retrospectively analyzed for their clinicopathological characteristics. Relevant literature was reviewed. Results: All 24 cases of NUT midline carcinoma occurred in the chest or head and neck, including 14 men and 10 women, with a median age of 40 years. Histological examination showed that the tumors were poorly differentiated, with solid nested or sheet-like arrangement, small to medium-sized cells, sparse cytoplasm and coarse granular chromatin, including 5 cases with abrupt squamous epithelial differentiation. Immunohistochemistry showed that all 24 cases were positive for NUT protein, while 16 cases were p63 positive, 19 cases were p40 positive, 15 out of 18 cases were CK5/6 positive. Follow-up data were obtained for 21 patients (follow-up time range, 1-21 months), of which 11 survived, 10 died, and 3 were lost to follow-up. Conclusions: NUT midline carcinoma is a rare and highly aggressive malignancy with unique histological, immunophenotypic and molecular features. It has a poor prognosis.