1993 Volume 33 Issue 2 Pages 255-260
A 55-year-old male with idiopathic interstitial pneumonia had been treated with a corticosteroid for 19 months. In the course of treatment, malignant cells (squamous cell carcinoma) were confirmed by sputum cytology. His chest roentgenogram showed ring-like reticular shadows in the right lower lung field without any apparent tumorous shadow. Right middle and lower lobectomy combined with partial resection of right S2 was performed. The macroscopic findings on surgical specimens revealed only diffuse stiffness within the parenchyma of the honey comb lung in the subpleural area of the lower lobe, and it was difficult to determine the primary site of the tumor. Histologically, honeycomb formation and fibrous wall thickening were noted in the lower lobe, throughout which atypical squamous metaplasia and squamous cell carcinoma were scattered. In part, transition from squamous metaplasia to carcinoma was observed. Squamous cell carcinoma of the lung rarely proliferates in such a fashion and it was suggested that lung cancer accompanying idiopathic interstitial pneumonia might develop multifocally.