A huge pleural hydatid cyst with significant shift of mediastinum

Echinococcosis, or hydatid cystic disease, is caused by the larvae of the Echinococcus tapeworm. The annual incidence may be as high as 13 to 27 cases/1,000,000 in certain parts of central Asia. Its incidence in Iran is still high. If they pass the obstacle of the liver, they are arrested in the lung. There is also evidence that the disease can be transmitted through the bronchi. Also, it has been theorized that extra parenchymal and intrathoracic hydatids may develop inside of the chest wall via transmission of the lymphatics of the chest wall [1]. Pleural involvement is rare and usually follows the rupture of a pulmonary or hepatic cyst inside the pleural space causing secondary pleural hydatidosis. Intrathoracic yet extra pulmonary locations are infrequent, with an occurrence rate of 7.4% [2]. It may be primarily caused by direct haematological or lymphatic larval seeding or secondarily as a late complication of surgery or chest tube insertion during therapy for thoracic hydatid disease [3].
Herein we present the case of a 33-year-old female, who came to us with the complaint of gradually worsening dyspnoea for the preceding 4 months. Clinical examination revealed decreased breath sounds over the right lung. Computed tomography (CT) scan of the thorax and abdomen showed a huge cyst in the right hemithorax containing many daughter cysts, which led to complete lung collapse and a significant shift of the midline structure with simultaneous liver hydatidosis. Most probably a large liver cyst raised the diaphragm and caused lung collapse and shifted mediastinal structure, so the patient was ready for thoracotomy (Figure 1).
Right posterolateral thoracotomy through the 6th intercostal space was done. Due to the large size of the cyst, and in order to prevent spillage of the cyst, after partial cutting of the intercostal muscles, using a special trocar, some of the contents of the cyst were drained and then a complete incision was made through the entire thickness of the muscles. We encountered a large pleural hydatid cyst that contained a lot of daughter cysts (Figure 2).
By performing the principles of complete evacuation, hydatid cyst drainage was done. After complete evacuation of the daughter cysts, the membrane of the pleural hydatid cyst was carefully removed from the thoracic wall, lung parenchyma, pericardium, and diaphragm. The pulmonary parenchyma was highly intact. The membrane of the cyst had communication with the...


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