Background: Hydatid disease is a parasitic infestation by a tapeworm of the genus Echinococcus. Man is an intermediate or accidental host of this parasite, and is infested by consuming contaminated plants or vegetables, or by contact with dogs. The larvae travel through the gut wall and 60-75% are filtered by the liver, and a few travel directly to the lungs to produce a hydatid cyst there. Growth of hydatid cysts has been reported in the spleen, muscles, bones, and brain. Hydatid cyst embolism to peripheral limb arteries is extremely rare.

Case: A 41-year-old gravided woman presented with sudden pain, erythema and warming of the olden infra-inguinal mass which existed from 1 year ago. The notable findings at physical examination included 40*20 mm diameter soft mass with warming and erythema in 4 cm below inguinal ligament of right lower limb. She didn’t mentioned any previous history hydatid cyst. Intraoperatively, Percutaneous aspiration of the mass was performed which demonstrate white turbid fluid. after the surgical incision we saw the white colored subcutaneous hydatid cyst and completely remove it and send it to pathological examination which confirmed hydatid cyst diagnosis. further liver ultrasound and chest radiography hasn’t shown any evidence of liver or lung involvement.

Conclusion: Cystic echinococcosis may affect all organs, but mostly settles in the liver and lungs. We do not have data on the means by which the larvae of echinococcosis reach the inguinal area without liver and lung involvement. Considering the anatomy of the groin and its lymphatic tissue, we can make an assumption about how the hydatid cysts settle in the groin space. Although it occurs rarely, larvae in the gastrointestinal tract may pass to the lymphatic circulation, and then settle in the groin space through the rich lymphatic flow of inguinal area.