Infected primary hydatid cyst of retroperitoneum.

An infected primary solitary hydatid cyst of the retroperitoneum that displaced the right kidney and liver and elevated the diaphragm is described. It showed pericystic calcification and contained an air-fluid interface. No other hydatid cyst was demonstrable in any organ. The cyst was treated by surgery together with povidone-iodine irrigation and albendazole prophylaxis for secondary infestation. In these lesions, increased CT density of the mother cyst and lower densities of the daughter vesicles are pathognomonic. In the present case, secondary bacterial infection further increased the CT density of the mother cyst, while the daughter vesicles remained uninfected and were visible as lower densities.