[Aneurysm of the pulmonary artery].

Schistosomiasis is an ancient and endemic disease in Egypt. It exists under two varieties: a haematoblum and a mansoni. The worms of the former produce ova with a terminal spine which they deposit in the small veins of the urinary system, while in the latter the worms favor the intestinal tract and their ova have a lateral spine. S. mansoni is prevalent in the lower Nile Delta and is commonly attended with visceral complications in the liver, spleen and lungs, while S. haematobium is more frequent in the upper Nile Valley and its noted complications are mainly urinary. The earliest clinical recognition of schistosomiasis of the cardiopulmonary system was first reported by Azmy, Effat and Sorour in 1932, which disease they labelled Bilharzial Ayerza; later an extensive pathological study from the same school was conducted by Shaw and Ghareeb in 1938. Though Schistosoma worms may reach the pulmonary artery or its branches and upon their death (accidentally or from antimony treatment) may follow a verminous dull congested lobular pneumonic allergic infiltrations, yet the usual picture is not due to the migrated worms but is due to the deposition of living ova In an around the terminal pulmonary arteriole. Schistosoma mansoni ova are particularly injurious, In that respect, especially to the vessels, though the incidence of schistosoma haematobium deposited ova may be higher In the lung. There are two main forms of pulmonary schistosomiasis which are by no means Individually separate; a cardiovascular and a parenchymatous, the one often merging into the other. The ova reach the lesser circulation either from the vesical veins in the schistosoma haematobium or across a porto-caval anastomosis in S. mansoni, the residence of which is confined to the portal tract. Only living ova are capable of exciting a histiocytic and a fibroblastic reaction in and around the arteriole, which they are capable of penetrating. They lie in its Immediate vicinity causing an end-arteritis obliterans and the so-called bilharzlal tubercle which is 0.5 to 1 mm. in diameter, greyish In color, firm in consistency