NUT expression in primary lung tumours

BACKGROUND: Nuclear protein in testis (NUT) midline carcinomas (NMC) are rare, highly aggressive epithelial neoplasms, characterised by protein expression of NUT-fusion proteins which reflects the genetic translocation between chromosome 15 and 19. NMC occurs mainly in midline structures, but there are reports regarding occurrence in structures outside the midline. We investigated specimens from 519 surgically resected lung carcinomas and carcinoid tumours for the presence of NUT protein using immunohistochemistry. Normal testis and two previously confirmed NMCs served as positive controls. FINDINGS: All 483 evaluable cases (278 adenocarcinomas, 140 squamous cell carcinomas, 30 large cell carcinomas, 7 small cell carcinomas, 10 undifferentiated carcinomas and 18 carcinoids) were completely negative for expression of NUT protein. CONCLUSION: NUT gene rearrangement does not seem to be relevant in primary pulmonary carcinomas or carcinoid tumours of the lung.