Hydatid cyst of the neck mimicking a branchial cleft cyst.

Here we report a rare case of primary hydatid cyst with involvement of soft tissue of the neck in a child. A 4-year-old girl presented with gradual swelling of the right side of her neck over a period of several months. The lump was fairly soft and painless with no significant inflammation. There was no other abnormal finding in the physical examination. Imaging was performed by ultrasonography followed by neck CT scan which demonstrated a simple cyst as the cause for the neck bulging. With the presumed diagnosis of a branchial cleft cyst, surgical resection was performed. Hydatid cyst was confirmed in pathology. Isolated soft-tissue hydatid cyst is an uncommon finding which should be considered in the differential diagnosis of soft-tissue cystic lesions especially in endemic regions. This is of more significance in children in whom congenital cysts of head and neck are more common.