Squamous cell carcinoma showing lobar consolidation without collapse

Most squamous cell carcinoma of the lung arises in the large bronchi and causes bronchial obstruction. We report a 74-year-old man with a squamous cell carcinoma of the lung whose roentgenogram revealed a lobar consolidation without collapse. A postmortem examination showed that the tumor cells filled the alveolar spaces completely without destroying the original architecture of the lung. The finding that tumor cells replacing alveolar epithelium, as in bronchioloalveolar cell carcinoma, was not seen throughout the lung. Airway obstruction by the tumor was not observed at any bronchus. These pathological findings seemed to explain the radiological findings.