Microscopic tumour emboli to the lungs: a hidden cause of dyspnoea and pulmonary hypertension.

Although the syndrome of "subacute cor pulmonale" caused by multiple tumour emboli to the pulmonary arteries has been well-described,' few reports have recorded detailed haemodynamic measurements from the pulmonary circulation in this setting. We describe a woman with known metastatic breast carcinoma who developed dyspnoea of hidden origin. Perfusion lung scanning and pulmonary angiography with haemodynamic recordings were performed, and the results demonstrate not only the development of remarkable pulmonary hypertension, but also the difficulty of antemortem diagnosis of the syndrome when emboli involve only the small arteries and arterioles.