Hydatid disease is the most common human cestodiasis . The HC is an anthropozoonosis due to the development of cysts corresponding to the larval form of a taenia called Echinococcus granulosus [1, 6]. This parasitic disease is still endemic in Tunisia. The liver and secondly the lungs are the two most common locations of hydatid cyst [1, 2, 7, 8]. In the diagnosis at an advanced stage of the disease, the hydatic cyst of the lung is correlated with more infectious and compressive complications due to increased size. Giant hydatid cysts of the lung constitute a particular clinical entity most frequently encountered mainly in younger patient . The right lower lobe location is generally the predominant lung location [5, 10]. In our study, the most frequent localisation of the GPHC was the right lower lobe (39.39%) as cited in the literature.
Lung tissue has more elasticity and compliance than other organs so that HC typically grows quickly than in others tissues [3, 7, 10]. In addition, the peripheral location of the cyst gives rise to an increase in size more easily than a central cyst since in the latter, the main vascular structures and bronchi will limit growth of the cyst . The HC in the lung enlarges in size depending also on the patient’s immune response and pulmonary reserve . Moreover, in the literature review, it has been reported that the immune system and the relatively higher elasticity of the lung parenchyma in children and the adolescent allows the rapid growth of cyst, and hence giant hydatid cysts are more commonly seen in young people than in elderly people. In our study, most of our patients (69.69%) are younger than 40 years.
There is no universally accepted size to define a pulmonary hydatid cyst as “giant” [7, 8]. However, according to the majority of articles published, it was agreed that 10 cm or more defined the size of giant hydatid cysts of the lung [5, 7, 12]. Compared to smaller cysts, GPHC require various surgical techniques that depend on per-operative founding. Generally, the lung hydatid disease is asymptomatic for a long time until occurrence of local or general complications such as rupture into the bronchi and pleural cavity or vital organ compression [3, 13]. Those complications are more frequent in case of GPHC due to the size of the cyst, and so symptoms appear usually [1, 3, 9]. In our study, all patients were symptomatic.
Generally, the diagnosis of hydatid disease is easy in endemic areas . Chest X-ray provided accurate diagnosis of GPHC in 93.4% of cases . The CT scan is not mandatory for diagnosis, but in case of GPHC, it enables to specify the size of the cyst and allows better information about the extent of the cyst in lung parenchyma, bronchi, and pulmonary vessels . Occasionally, complicated GPHC constitute diagnostic challenges on imaging, and the per-operative exploration is the only one that provides a final diagnosis .
The surgical challenge in GPHC is to remove the giant cyst while preserving as much lung tissue as possible . Decision-making criteria in the choice of operative techniques differ from one country to another and are inextricably depending to the thoracic surgeon’s experience with the lung hydatid disease . In addition, usually, it can be difficult to predict preoperatively whether anatomical resection will be required.
Surgical approaches in our study were posterolateral or lateral thoracotomy depending on the cyst location. We did not use VATS in our patients because in case of intact cyst which is under tension and seen the risk of rupture, we prefer to avoid introduction of trocar; secondly, we might have enough access to thoracic cavity in order to perform laborious capitonnage.
The size of the HC and the presence of complications are the most commonly accepted criteria for deciding which surgical technique should be performed . Is widely accepted that lung-preserving parenchyma-surgery is preferable . Cystotomy with capitonnage after the closure of small bronchial communication or fistula constitutes the routine conservative surgical techniques of the GPHC . It is believed that those procedures should be preferred in most cases because the lung parenchyma that has been compressed by the cyst is healthy and would expand postoperatively. Anatomical resection should be avoided whatever the cyst size . However, for many authors, it is advised to perform an anatomical resection when giant cysts occupying the entire lobe and if GPHC is associated to complications (suppuration, chronic abscess, fibrosis, haemorrhage…) that causes parenchymal damage by involving more than 50% of a lobe [1, 3, 10]. For other authors, the decision of anatomical pulmonary resection are taken in per-operative, after aspiration of cystic fluid, the closure of bronchial openings, excision of the cyst, and testing of the lung re-expansion of the remaining lobe.
In our study, anatomical resection is relatively high and was performed in 15 patients (45.46%). Six patients had a complicated large cyst ( mainly hemoptysis), and nine had an intact GPHC, which is associated with lung resection irreversible damage which have occurred throughout the lungs by involving more than 50% of a lobe or those that are associated with such sequelae such as chronic abscess, bronchiectasis, or severe haemorrhage; thus, lobectomy or bi-lobectomy is required.
Two main reasons argue for lung-preserving parenchyma surgery and push the surgeon to avoid anatomical resection. First is the high probability that the pulmonary parenchyma remaining after conservative surgical procedure can ensure satisfactory re-expansion of the lung. Secondly, mainly in the endemic country, there is a higher risk of recurrence of hydatid disease and so the possibility of iterative surgery of hydatid cyst .
Morbidity rate of GPHC surgery can be very low with a negligible mortality rate, if the capitonnage is properly performed, and the bronchial openings are firmly closed . The complication rates reported in the literature varies between 17 and 19% in giant hydatid lung cysts . In our study, the complication rate was 24.25%. Even though GPHC in our study were likely to require anatomic lung resection, we were able to perform parenchyma-sparing operations in 54.54% of the cases.
Preoperative medical treatment with albendazole (ABD) treatment decreases the tensile strength of the cuticular membranes of pulmonary HC and might cause rupture of the cyst. Therefore, it should not be applied to patients who are candidates for surgery. Perhaps, it can be administered preoperatively, for patients with multiple cysts or ruptured ones. In postoperative, ABD can be given to patients having a risk of intraoperative spillage or patients with giant cysts to prevent recurrence . For other authors, it is post-operatively administered medical therapy only if daughter cysts are detected during the operation . In disseminated and nonoperable cases of lung HC, therapy with ABD can be used as an alternative to surgery. In conclusion, reported in the literature and our experience, we think that medical treatment with ABD of HC of the lung should be performed in inoperable cases and can be used during the postoperative period, in order to prevent the recurrence and occurrence of a secondary cyst [3, 12].