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Tex Heart Inst J. 2010; 37(4): 429–434.
PMCID: PMC2929855

Surgical Management of Pulmonary Hydatid Cysts

Is Size an Important Prognostic Indicator?

Abstract

Giant hydatid cysts of the lung (diameter, ≥10 cm) are considered more difficult to treat surgically than are smaller cysts. We reviewed our experience with giant pulmonary hydatid cysts, focusing on clinical symptoms, cystic location, extent of surgery, and postoperative complications, according to age, long-term results, and comparison with non-giant cysts. From January 1988 to January 2008, 537 patients underwent surgery for pulmonary hydatid cysts. We separated patients into 2 groups: patients who had cysts <10 cm (group A) and those who had giant cysts (group B). Group B comprised 75 patients (14%). Giant cysts were more common in younger patients (mean age, 30 vs 32 yr; P=0.014). The most frequent complaints were cough, chest pain, and dyspnea. Patients with giant cysts were more often symptomatic at presentation (96% vs 88%; P=0.04). In both groups, lower-lobe locations predominated. Parenchyma-saving operations were almost uniformly performed for each group; however, a higher percentage of patients in group B required anatomic resection (4% vs 1%; P=0.038). Fifty-seven patients (10%) also underwent resection of concomitant liver cysts. Cystic rupture occurred more frequently in group B than in group A (27% vs 15%; P=0.01). There were no deaths in either group, nor were there significant differences in morbidity between groups.

In summary, giant hydatid cysts of the lung occurred more often in younger patients and were more often symptomatic at presentation. Regardless of size, the cysts could usually be surgically treated without lung resection, and size did not appear to influence short-term perioperative outcomes.

Key words: Adolescent, adult, age distribution, age factors, aged, child, albendazole/therapeutic use, echinococcosis, hepatic/surgery, echinococcosis, pulmonary/surgery, Horner syndrome/etiology, hydatid cyst, middle age, retrospective studies, treatment outcome

Hydatid cysts are the most common parasitic disease of the lungs. They are a major health problem in agricultural countries that lack satisfactory preventive medicine, environmental health, and veterinarian services. Hydatid disease is endemic in the eastern and southeastern regions of Turkey.1 Hydatid cysts of 10 cm or greater in diameter are called “giant” cysts and traditionally have been considered to be more difficult to treat surgically—often requiring pulmonary resection. We aimed to retrospectively evaluate our institutional experience with surgically treated hydatid cysts to investigate whether cystic size is really an important factor in terms of clinical outcome.

Patients and Methods

From January 1988 to January 2008, 537 patients underwent surgery in our department for parenchymal hydatid cysts. This number does not include patients with intrathoracic extrapulmonary cysts, who were excluded from the study. Hydatid cysts were categorized into 2 groups, in accordance with radiologic and operative findings: those smaller than 10 cm (group A) and those 10 cm or greater (group B). There were 462 patients (86%) in group A and 75 patients (14%) in group B. The clinical characteristics of both groups are shown in Table I.

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TABLE I. General Characteristics of the Patients

In the event of bilateral hydatid cysts, surgery was performed first on the larger cysts. Preoperative chest radiography (Figs. 1 and and2)2) and computed tomographic scanning (Fig. 3) were performed on all patients, as was ultrasonography of the abdomen—this last to determine whether hydatid cysts were present in the liver. Percutaneous transthoracic needle aspiration was not performed for diagnosis or treatment. In the early years of the study, Casoni's intradermal test and indirect hemagglutination test were performed; later, the enzyme-linked immunosorbent assay test was substituted for Casoni's intradermal test. If hydropneumothorax and cystic rupture developed preoperatively, the pleural cavity was first drained by means of a tube thoracostomy. All patients underwent operation as soon as conditions were optimal. Patients who presented with simultaneous liver and lung cysts underwent thoracotomy and resection of the pulmonary cyst first. If the liver cyst was located at the dome of the liver, a radial incision was made in the diaphragm, through which the cyst was injected with hypertonic saline. If liver cysts were located deeper, within the parenchyma of the liver, they were treated at a later stage via a separate laparotomy. Patients who presented with ruptured cysts or who sustained intraoperative spillage of cystic fluid were treated with albendazole. In recent years, albendazole has been used on all patients during the postoperative period. Patients were monitored for a minimum of 1 year and a maximum of 5 years.

figure 6FF1
Fig. 1 Radiograph (posteroanterior view) shows giant hydatid cysts with bilateral involvement.
figure 6FF2
Fig. 2 Radiograph (lateral view) shows giant hydatid cysts with bilateral involvement. This is the patient shown in Figure 1.
figure 6FF3
Fig. 3 Computed tomogram shows giant hydatid cysts with bilateral involvement.

Surgical Technique

A posterolateral thoracotomy was performed on most patients. For bilateral lung cysts, we performed sequential bilateral thoracotomies; however, more recently, we have preferred to approach in a single procedure via median sternotomy. The results have been gratifying (Fig. 4). Thoracotomy was performed through the 5th, 6th, or 7th intercostal space, depending on the location of the cyst. Every effort was made to avoid rupturing the cyst while incising the intercostal muscles.

figure 6FF4
Fig. 4 Radiograph (posteroanterior view) shows the patient shown in Figure 1, after excision of bilateral giant hydatid cysts.

In order to prevent the thoracotomy site and the surrounding tissues from being flooded by cystic material, we protected the operative field with compresses soaked in hypertonic (20%) sodium chloride solution. If the cyst was intact, it was aspirated at its most superficial point. Scolicidal agents were not used. Aspiration was accomplished with a 10-G lumbar puncture needle connected directly to the aspirator. Once the cyst's pressure decreased, 2 Allis forceps were clamped to hold the pericystic layer and the parasite's membrane inside. The purpose of this process is to prevent the parasite's membrane, upon the reduction in pressure, from falling into the fluid and thereby flooding the pericystic cavity and bronchus. After the aspiration of as much fluid as possible, the pericystic and cystic membranes were simultaneously incised between the 2 clamps, and the clamps were repositioned in such a manner as to hold the edges of both membranes. The fluid was completely drained by placing the tip of the aspirator directly into the cavity formed by the parasite's membrane. Then only the pericystic layer was held with the Allis forceps, and we removed the cystic membrane. The residual cavity was cleaned with gauze that was saturated with hypertonic sodium chloride and povidone-iodine solution.

In order to look for bronchial openings, we filled the pericystic cavity with a physiologic serum. We inflated the lung, checked for air leaks, and closed any bronchial openings with 2-0 nonabsorbable suture material. We usually performed capitonnage, either vertically by closing the edges of the cyst with continuous sutures from the lower part of the cavity to the upper part, or horizontally after resecting the free parts of the pericyst.

We administered albendazole preoperatively to patients with ruptured pulmonary cysts or with cysts considered to be at risk of perioperative spillage of parasitic material. We also administered albendazole postoperatively, for the purpose of prophylaxis, to patients who had undergone simultaneous surgery for liver cysts. Treatments were given as sequential 28-day courses, with 14-day intervals between courses. Between courses of treatment, liver-function tests were conducted.

Statistical Analysis

Univariate analysis of categorical variables was performed using the χ2 test or the Fisher exact test. All statistical tests were 2-tailed and the χ2 test (when expected cell counts were ≥5) or the Fisher exact test (when expected cell counts were <5) was used to determine the significance of differences in categorical variables. A significance level of P <0.05 was adopted in all analyses. Analyses were performed with SPSS (Statistical Package for the Social Sciences) version 11.0 (SPSS Inc.; Chicago, Ill).

Results

Age and Sex. Group A consisted of 462 patients of whom 259 were female (56%) and 203 were male (44%). The mean age of the group A patients was 32.4 years (range, 5–81 yr). Of the 75 patients in group B, 39 were female (52%) and 36 were male (48%). The mean age of the group B patients was 30.4 years (range, 4–72 yr). The distribution of sex was not significant (P=0.5), but the 2 groups revealed significantly diverse age distribution. Most patients in group B were 16 to 30 years of age, while most group A patients were 31 to 45 years of age.

Symptoms. The most common symptom in group A was coughing, while it was chest pain in group B. Other symptoms included hemoptysis, fatigue, dyspnea, hydatoptysis, vomiting, and fever (Table II). The percentages of symptomatic patients in groups A and B were 88% and 96%, respectively (P=0.04).

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TABLE II. Distribution of the Patients According to Symptoms

Location. There was no significant difference in the frequency of bilateral cysts between group A and group B (6% vs 10%; P=0.21). Overall, right-lung involvement was more common than left-lung involvement. Rates of right-lung involvement were similar for groups A and B (58% and 61%, respectively). The right lower lobe was the most commonly involved location in both groups (Table III). Simultaneous involvement of the liver occurred in 45 group A patients and in 12 group B patients. Rates of hepato-pulmonary hydatid cysts were not significantly different in the 2 groups (P=0.1).

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TABLE III. Locations of Lung Cysts within the Groups

Apart from the liver, neighboring structures—such as the chest wall, diaphragm, and pericardium—were involved in 26 patients (5%). For these patients, no additional surgical intervention, except for pleural decortication, was required.

Size of Cysts and Age of Patients. Hydatid cysts less than 10 cm in diameter were subdivided into 3 groups. The hydatid cysts 4 to 6 cm in diameter were seen more frequently in group A. Giant cysts were more common in younger patients (P=0.014). See Table IV for a breakdown by age of patients and diameter of cysts.

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TABLE IV. The Relationships between Age of Patients and Diameters of Hydatid Cysts

Condition of Cysts. In group A, 395 patients (86%) had intact cysts, and 67 (15%) had ruptured cysts. Fifty-five group B patients (73%) had intact giant cysts, and 20 group B patients (27%) had ruptured cysts (P=0.01).

Surgical Procedures. In group A, 3 patients (0.06%) required lobectomy, and the remaining 459 patients underwent drainage–capitonnage or cystectomy. Pleurectomy and decortication were required in 21 patients (4.5%). In group B, 3 patients (4%) underwent lobectomy, and the remaining 72 patients underwent drainage–capitonnage or cystectomy. Pleurectomy and decortication were performed in 5 of these patients (7%) (Table V). Lobectomy rates were significantly higher in group B, compared with group A (P=0.038). There was no significant difference between groups in the use of pleurectomy and decortication. In 20 of the 57 patients with a simultaneous hydatid liver cyst, we performed a transdiaphragmatic approach and injected the cyst with hypertonic saline solution.

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TABLE V. Distributions of Operation Types

In cases of concomitant hepatic hydatid cyst on the dome of the liver, single-stage surgery of both lung and liver cysts is a practical approach.2,3 In 20 of our 57 patients with a hydatid cyst in the liver (11% of the 537 patients in the study), we approached the liver cyst via a small radial diaphragmatic incision, in addition to the thoracotomy for the lung cyst. These 20 patients did not require a thoracoabdominal incision.

Postoperative Sequelae and Follow-Up. The most common postoperative complication in both groups was prolonged air leak, which occurred in 27 group A patients (6%) and in 6 group B patients (8%). Other postoperative complications were pneumonia in 18 (4%) group A patients and in 4 group B patients (5%); empyema in 10 group A patients (2%) and in 3 group B patients (4%); and Horner syndrome in 3 group A patients (0.6%) and in no group B patients. Horner syndrome, believed to have been caused by chest tube irritation of the ipsilateral sympathetic nerve,4 disappeared spontaneously after the removal of the tube.

There was no respiratory failure and no patients needed long-term mechanical ventilation. There was no 30-day or in-hospital death. The mean hospitalization period was 7 days, and group A did not significantly differ from group B in that regard (P=0.27).

Discussion

Due to the elasticity and compliance of the lung parenchyma, hydatid cysts typically grow faster in the lung than in other organs. Therefore, larger cysts are more common in the lung, where they can grow from a few millimeters to 5 centimeters in 1 year.5–7 Furthermore, cysts appear to grow faster in young people than in elderly people. The relationship between the diameter of cysts and the age of our patients is an important and statistically meaningful feature of our study. In our study, hydatid cysts were more commonly seen in patients aged 45 years and younger; in patients older than 60 years, cysts diminished both in frequency and in size.

As other reports have shown, the prevalence of hydatid cysts was greater in the right lung and in the lower lobes of both lungs.2,5,8,9

Pulmonary cysts can enlarge substantially without symptoms; but, in general, symptoms depend on the size and location of the cyst, on the amount of pressure the cyst exerts on surrounding tissues, and on whether or not the cyst is ruptured.10 Although most patients who present with hydatid cysts are symptomatic, in our study patients with giant cysts were more frequently symptomatic than were patients with smaller cysts.

Rupture of a cyst into the pleural space or bronchus can cause an anaphylactic reaction. Furthermore, obstruction of the tracheobronchial tree with cystic membrane can lead to suffocation.5 Therefore, hydatid cysts should be operated upon as soon as they are diagnosed. In our study, giant cysts showed more potential to rupture than did smaller ones (27% of cysts ruptured in group B, versus 15% in group A). Cystic rupture establishes a basis for infection and parenchymal destruction. In 3 patients in our study, anaphylactic reaction occurred and manifested itself as low-degree skin eruptions.

Of the structures that constitute the cyst, the laminated membrane, germinative membrane, and cystic fluid are formed by the parasite, but the pericystic membrane is formed by the host. Because the laminated membrane, germinative membrane, and cystic fluid are removed, we call the surgical procedure a cystectomy.

Surgery remains the treatment of choice for hydatid cysts of the lung, and a parenchyma-saving operation is usually possible. Preservation of the parenchyma is fundamental to the surgical management of these cysts. However, in cysts that cause parenchymal damage by involving more than 50% of a lobe or that are associated with such sequelae as chronic abscess, bronchiectasis, or severe hemorrhage, lobectomy is performed.5,11 Often, it can be difficult to predict preoperatively whether lobectomy will be required. Only after the cystic fluid has been aspirated, the bronchial openings closed, and the lung inflated, do we decide whether to perform resection.

In our series, the percentages of cysts that caused parenchymal damage were 4% in giant cysts and 1% in normal-sized cysts, slightly lower than the rates of 7% to 13%6,12 reported in the literature; but selection bias certainly could play a role in these differences. Even though giant cysts in our series were statistically more likely to require anatomic lung resection, we were able to perform parenchyma-sparing operations in the overwhelming majority of cases (96%).

In the medical literature, morbidity rates for all hydatid cyst surgery range from 3.5% to 27%, whereas mortality rates range from 0 to 2%.6,8,9,13–16 If the number of complicated cysts is low, the bronchial openings are firmly closed, and capitonnage is properly performed, the morbidity rate of hydatid cyst surgery can be very low and the mortality rate almost zero. In our study, the overall morbidity rate was 13% (12% vs 17%, in groups A and B, respectively; P=0.27), and the mortality rate was zero.

There are some reports that small cysts can be cured with albendazole.13,17 However, we have observed that patients who do not undergo surgical therapy develop ruptures, infections, and hemoptysis after isolated albendazole treatment. That is why we prefer surgical treatment of hydatid cysts.

In conclusion, we found that giant hydatid cysts of the lung were more prevalent than smaller cysts in younger age groups, perhaps because the compliance and elasticity of the lung in younger patients enable hydatid cysts to develop into larger sizes before they become symptomatic. Indeed the diameters of hydatid cysts vary among age groups, with the incidence of giant hydatid cysts declining gradually in persons over the age of 45 years. Cysts that develop into giant sizes in the young can lead to life-threatening results. Due to the potential sequelae, all patients with hydatid cysts, especially giant ones, should undergo surgery as soon as the diagnosis is made. Despite statistically higher rates of rupture among patients with giant cysts, and a slightly higher requirement for anatomic resection, we did not encounter any significant differences in postoperative sequelae or length of hospital stay. Surgery for hydatid cysts of the lung, whether giant or otherwise, can be safely performed, with low morbidity and negligible mortality rates, and is the treatment of choice.

Acknowledgment

We gratefully acknowledge the assistance of Dr. David C. Rice in the preparation of this manuscript.

Footnotes

Address for reprints: Ozan Usluer, MD, Mustafa Kemal Caddesi No:95/1 D:14 Bornova, 35040 Izmir, Turkey

E-mail: moc.oohay@reulsunazo

References

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