A 7-year-old boy presented with a painful swelling on his chest wall under the left clavicula. His parents reported that this mass had developed and increased in size within the previous year. Physical examination showed a fluctuant mass (3 × 4 cm) within the indicated region; this mass elicited pain on palpation. Ultrasonographic examination did not reveal any diagnostic clues. Considering that the patient’s family lived in a region endemic for hydatid disease and were involved in livestock farming, the patient underwent further assessments using abdominal and thoracic computed tomography (CT) examinations, specific immunoglobulin E (IgE) tests, and hemagglutination tests to confirm a diagnosis of hydatid cyst. The serologic test results were normal. CT did not show any cystic lesions in the liver, lungs, or other intraabdominal organs (Figure A). However, a mass, measuring 28 × 38mm, similar to a unilocular cyst, was observed on the anterior thoracic wall just below the left clavicle (Figure B). For definitive diagnosis, and treatment of the mass, excisional biopsy was scheduled. The mass was excised in compliance with the principles of the surgical procedure; however, the cyst wall ruptured revealing a germinative membrane. The mass was extirpated, and prepared for histopathological examination (Figure C). On the basis of the findings of the histopathological examination, a diagnosis of hydatid cyst was confirmed.
