Distribution of lung metastases in the axial plane. A combined radiological-pathological study.

The appearance of lung metastases and their distribution in the axial plane was studied on radiographs of formalin-vapour inflated fixed lungs. The results show that the vast majority of lung metastases are to be found at the periphery of the lung, irrespective of cavitation or of their shape or size. This distribution cannot be explained by hydro-dynamic factors, but may be related to the susceptibility of metastases in different parts of the lung. the metastases were also analysed as to their appearances, namely well-defined nodular, star-like, ill-defined edge and cavitating. No definite correlation with distribution was apparent but when extremely numerous, metastases were usually less than 1 cm in diameter with ill-defined margins. This could be due to their rapidity of growth.