An Unusual Location of Hydatid Cyst, Cause of Severe Pollakiuria

Hydatidosis is an important zoonotic parasite disease in several herbivorous mammals. Human cystic echinococcosis (CE) caused by infection with larval stage of Echinococcus granulosus has been frequently reported from different organs. Here, we report the first case of a urinary echinococcosis in Iran with a pain in the lower left abdominal quadrant and severe frequent urination (pollakiuria). We detected a cyst 120 × 15 mm dimensions with heterogeneous mass contain fluid in the back of the urinary bladder neck between the umbilical region and external urethral sphincter. The patient was candidate for open-abdomen surgery and cysts were resected. The isolated cysts from liver and urinary bladder were referred to pathology laboratory, and the tissue sections were stained with Tri-chrome and Hematoxylin/eosin staining methods. Microscopic examination of prepared tissue sections showed protoscoleces of E. granulosus with specific and thick laminated hyaline layer (non-cellular membrane), with covers the thin activate germinal epithelium, which revealed the diagnosis of a hydatid cyst. This rare case illustrates that CE is the necessity of considering in the differential diagnosis from cysts, abscesses, malignant and benignant tumors, especially is essential in endemic areas of CE.