Case report of a pan‐cytokeratin negative NUT midline carcinoma of pulmonary origin, a BRD3‐NUT variant: Challenges in cytomorphologic presentation

NUT carcinoma is an aggressive malignancy defined genetically by a balanced translocation of the NUT gene on chromosome 15q14, most commonly associated with the bromodomain-containing protein 4 (BRD4) gene on 19p13.1 but less frequently with variant genes, including BRD3 and NSD-3. We present a case report of a metastatic pulmonary NUT carcinoma found to have a BRD3-NUT fusion and to have only focal pan-cytokeratin staining. Biopsy of the …