[Arteriovenous aneurysm of the lung].

Arterio-venous aneurysm of the lung is usually considered to be a rare lesion, and by 1942 only four examples were on record. During the last six years, however, nineteen more cases have been published, and it is likely that as the clinical features of this syndrome become better known still more of these patients will be separated from the cases of cyanotic congenital heart disease and polycythaemia rubra vera with which they are often confused. Although the lesion has been described by some writers as a cavernous haemangioma, we believe, for reasons discussed below, that it is an arterio-venous aneurysm and not a true vascular tumour. The presence of the arterio-venous aneurysm causes a proportion of the venous blood in the pulmonary artery to be shunted directly into the pulmonary vein without passage through the lung capillaries. Venous blood returns to the left side of the heart to mix with the'arterial blood of the systemic circuit and thus to cause cyanosis, dyspnoea, and compensatory polycythaemia. The aneurysm may bring about the patient's death through haemoptysis, or cause dyspnoea which is incapacitating. Hepburn and Dauphinee (1942) were the first successfully to excise an arterio-venous aneurysm of the lung, and in the same year Shenstone's patient was cured by pneumonectomy. Since that time removal of the aneurysm either by lobectomy, or by local resection when the lesion is multiple (Janes, 1944), has become the accepted method of treatment, and with the recent advances made in the technique of thoracic surgery excellent results are to be expected. In this paper we report the case histories of two patients with arteriovenous aneurysms of the lung, and proceed to discuss the pathology of these " tumours " and the characteristic clinical picture to which they give rise.