Thoracic outlet syndrome caused by hydatid cyst of the first rib-rare but important.

Hydatid cysts are usually located in the liver and lungs. Skeletal echinococcosis is relatively rare and that of the rib is exceptional. Less than 50 cases of costal echinococcosis have been reported in the literature so far. To our knowledge, only one case report of thoracic outlet syndrome due to echinococcal cyst in the first rib was described in 1995. Accurate pre-operative diagnosis is important but may be challenging in some cases. Reported here is a case of echinococcosis of the first rib in a young adult who was presented with thoracic outlet syndrome. Plain chest radiograph, CT scan and MRI were performed. The imaging features were suggestive of a solitary aneurysmal bone cyst and the differential diagnosis included echinococcosis of the first rib. The lesion was completely resected and the histopathological examination confirmed the diagnosis of echinococcosis.