[Hydatic cyst in mediastinum].

The main localization of hydatic cysts (HC) in mediastinum is exceptional. We present the case of a 12 year-old boy who had habitual contact with dogs. He had pain in the right hemithorax and back together with low-grade fever. In the X-rays of the thorax a right retrocardiac image shows an occupied costodiaphragmatic sinus. The CT of the thorax shows a bilateral pleural effusion and a mass measuring 10 x 7.5 x 5 cm in the middle mediastinum. After admission, a new X-ray of the thorax revealed an increase in the right pleural discharge, for which reason an urgent thoracotomy was performed checking for the existence of a mediastinum HC with possible membrane fissures. The HC was removed. The only treatment of HC in mediastinum is surgical, an urgent thoracotomy being necessary whenever a possible rupture is suspected in order to avoid a possible anaphylatic reaction or growth pleural cavity.