Lung colloid adenocarcinoma: A multidisciplinary diagnostic challenge

Colloid adenocarcinoma of the lung is a rare subtype, often difficult to diagnose due to its indolent behavior and atypical imaging. We report a 76-year-old man and former smoker with an incidentally detected right lower lobe mass. Computed tomography (CT) showed a well-defined, lobulated lesion with poor contrast enhancement and internal calcifications and ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) demonstrated low uptake. Multiple percutaneous and surgical biopsies were nondiagnostic. Progressive growth and new onset of mediastinal lymphadenopathy ultimately led to right lower lobectomy, confirming stage IIIA colloid adenocarcinoma. This case highlights imaging limitations, the value of sequential biopsies, and the role of surgical biopsy when less invasive methods repeatedly fail, especially with high clinical suspicion.