Hyperacute Progression of Sinonasal NUT Carcinoma After Pembrolizumab-Based Treatment: A Case Report.

This case report describes hyperacute destructive progression of sinonasal NUT carcinoma with new osseous metastasis shortly after pembrolizumab-based immunochemotherapy. The clinical course highlights the importance of early NUT testing, proactive systemic surveillance, cautious interpretation of immunotherapy response, and timely consideration of BET inhibition or clinical trial referral.