Abstract
1. The radiological features of skeletal hydatid disease are discussed. Osseous lesions occur in about 1 to 2 per cent of cases, bone being involved only after the embryos have passed the filters provided firstly by the liver and secondly by the lungs. At first, ill defined areas of translucency appear which are not diagnostic. In developed lesions, clear-cut destructive areas, with a surrounding sclerotic reaction, become visible. The cysts thin and expand the cortex and tend to spread throughout an affected bone. In advanced stages the cortex is ruptured, and exuberant hydatid cyst growth takes place in the adjacent soft tissue. Around this an ectocyst forms, which may later calcify, indicating death of the parasite. The progress of the disease is very slow.
2. Three cases of affection of the thoracic spine are described, and the differential diagnosis is considered, particularly from plasmacytoma and neurofibroma. Each case presented with cord pressure symptoms. Operative decompression relieved these totally in one case, incompletely in another, and not at all in the third and most advanced case.
3. With rapid and easy travel in the modern world hydatid disease is liable to be seen in areas where it is not endemic.
