BRD3-NUTM1-expressing NUT carcinoma of lung on endobronchial ultrasound-guided transbronchial needle aspiration cytology, a diagnostic pitfall.

When a specimen demonstrates a dual cell population of squamoid cells and primitive-looking tumor cells in the wrong clinical context (i.e., young patient with no smoking history), further molecular profiling is warranted to include the differential of a primary NC of the lung. The cytological features of NC itself have rarely been documented and moreover, that of a primary NC of the lung with BRD3-NUTM1 fusion has never been reported. We herein report cytological findings of a primary NC of the lung with BRD3-NUTM1 fusion gene.