Radiologic-pathologic correlation between tumor edge and surrounding inherent structures in peripheral lung cancer

To evaluate the radiologic-pathologic relationship between the tumor edge of peripheral lung cancers and surrounding normal structures. Tissue samples from 16 lung cancers with diameters less than 2 cm were examined: 7 adenocarcinomas, 5 squamous cell carcinomas, 2 small cell carcinomas, 1 large cell carcinoma, and 1 that had metastasized to the lung. Inflation-fixed lung specimens containing tumor tissue were sliced to a thickness of 2 mm: The tumor edge of each section was traced under a stereomicroscope and its relationship to marginal structure, including bronchi, pulmonary arteries, and pulmonary veins containing interlobular septa, was analyzed. The tumor edge and marginal structures were classified into four types: Type 1, clear margin formed by marginal structures; Type 2, tumor involving the marginal structures; Types 3 and 4, marginal structures penetrating the tumor with and without a notch, respectively. Type 1 was found in 23 of 47 pulmonary arteries (49%), 23 of 49 bronchi (47%), and 12 of 31 pulmonary veins or interlobular septa (39%). Type 2 was found in 11% (14/127), Type 3 in 15% (19/127) and Type 4 in 28% (36/127) of marginal structures. Type 1 was common in all histological types of carcinomas studied. In small peripheral lung cancers, the tumor edge sometimes has a clear margin formed by surrounding structures such as interlobular septa. This can make it difficult to differentiate benign from malignant lesions.