Cavitary pulmonary metastases.

Cavitation in pulmonary metastases is more common than might be supposed from the small number of cases (75) previously reported. Twenty-five cases of cavitary pulmonary metastases were seen at the London Chest Hospital from 1964 to 1969. The primary sites were the large intestine (8), opposite lung (4), cervix (3), stomach, oesophagus, pancreas, and larynx (2 each) and anal canal and kidney (1 each). The size of the cavities ranged from 1·0 to 6·0 cm., and their wall thickness from 0·3 to 2·5 cm. Only in three cases was there an identifiable communication with the bronchial tree and only in these three cases were neoplastic cells found in the sputum. The main microscopic feature was vascular invasion, which was found in the vicinity of every metastasis; thrombosis was seen in 14 cases. It seems that the principal cause of necrosis and subsequent cavitation in metastatic tumours of the lung is interference with their blood supply by vascular involvement.