An Adrift and Homeless Cyst within the Peritoneal Cavity

INTRODUCTION: Echinococcosis is a zoonotic infection caused by Echinococcus species. Iran is endemic for Echinococcus granulosus. Here, we present a case of hydatidosis in an 85-year-old man, presented with acute, dull, constant, and generalized abdominal pain. A computed tomography scan (CT scan) showed an intact hydatid cyst on the bladder dome and several hydatid cysts in the liver. Open surgery revealed a cyst with hepatic origin, confirmed with histopathological studies. CONCLUSION: Although a primary abdominal hydatid cyst is very rare, it can be transferred to the abdominal cavity without any rupture as secondary ones. In this case, rupture of the liver wall was the reason for this transfer. As a result, there should be a suspicion of hydatidosis in a patient with a similar presentation.