Echinococcosis

Larval cysts may develop in various viscera, particularly the liver and the lungs, and may calcify, producing irregular curvilinear, eggshell-like cystic radiodense areas. Bone lesions may occur but a single bone, a few adjacent bones or one skeletal region is usually affected. The sites involved most commonly are the vertebral column, pelvis, long bones and skull.

Radiographically, the expansile cystic osteolytic lesions may reveal cortical violation and formation of a soft tissue mass, with calcification. CT scanning shows a soft tissue mass adjacent to sites of bone involvement. On MR images, numerous cystic lesions of high signal intensity in T2-weighted spin-echo sequences are characteristic. Pathologic fracture, secondary infection, rupture into the spinal canal, transarticular extension, and intrapelvic extension sometimes occur.

DR