Nuclear protein in testis carcinoma of the lung in an old-aged woman at an early stage

Nuclear protein in testis (NUT) carcinoma (NC) is a rare, aggressive malignancy often diagnosed late due to non-specific symptoms and low awareness. A 69-year-old woman presented with haemoptysis and a PET-avid lung nodule (cT1N0M0). Initial bronchoscopic biopsy suggested small cell carcinoma with negative NUT staining. Following lobectomy, immunohistochemistry showed strong nuclear NUT positivity, and FISH confirmed NUT rearrangement. This case was atypical due to the patient’s age, early stage, and initial misdiagnosis from limited biopsy. NC's non-specific presentation requires high suspicion, and small biopsies risk misdiagnosis.