Pulmonary hydatid disease.

Pulmonary hydatid disease is a particular radiological diagnostic problem when the hydatid is small, single, and symptomless, so that distinction must be made from the numerous other causes of isolated, peripheral pulmonary lesions. The technique of delivery of a pulmonary hydatid cyst, different from the management of other single peripheral lesions, makes preoperative recognition of hydatid disease important. Uncomplicated pulmonary hydatid cysts are seldom completely circular because they are so soft that they are dented and disfigured by adjacent structures-on this peculiarity of shape there is unanimity of opinion; that their outline is blurred in one or more places by areas of pneumonitis, haemorrhage or infarction (Barrett and Thomas, 1944), whose comprehensive paper carries the salutary and appropriate admonition cave canem as sub-title, is questionable-sharp definition, without adjacent pulmonary reaction, is typical of the solitary, small uncomplicated hydatid cyst (Shanks and Kerley, 1962). Close proximity to a pleural surface is common (Brown, 1958) but by no means invariable. Hydatid disease is endemic in the Natal midlands, that area to the east of the escarpment in the foothills of the Drakensberg mountains. Over a five-year period the diagnosis of isolated pulmonary hydatid cyst has been confirmed in 17 patients. Three were symptomatic-one because of vertebral hydatid disease (Fig. 1) and two because of rupture of the hydatid, into the pleura in one and into the bronchial tree in the other. The remainder were chance findings in patients for