Thoracic Hydatid Cysts: A Report of 842 Cases Treated Over a Thirty-Year Period

Thoracic Hydatid Cysts: A Report of 842 Cases Treated Over a Thirty-Year Period Zhongxi Qian, M.D. ABSTRACT From 1957 to 1985, 842 patients were diagnosed as having thoracic hydatid cysts; 810 cysts were intrathoracic, 29 occurred on the "liver roof," 2 were cardiac, and 1 was on the chest wall. A total of 1,010 surgical procedures were performed in 807 patients (35 refused operation). There was a total operative mortality of 0.6% (5 deaths). Procedures became more conservative as experience was gained, and 79% of the procedures were endocystectomies. Intact endocystectomy (Barrett's technique) without preliminary aspiration was the approach of choice. Careful protection of the operating field, suturing of all the bronchial openings, and capitonnage were the keys to successful treatment. One hundred six patients with intact endocystectomies done before July, 1975, were followed for 3 to 20 years. Ruptures occurred during cyst manipulation in 35 patients (33%). Recurrence after operation was seen in 2 patients (1.9%). There were no deaths among the patients undergoing intact endocystectomy. In comparison, we followed 136 patients who underwent aspiration endocystectomy and the recurrence rate was 3.7% (5 patients). Hydatid cyst is a parasitic disease caused by the larval growth of the tapeworm, Echinococcus grunulosus or Echinococcus ulveoluris. The latter species is very rare. All patients in our series had Echinococcus grunulosus. Infestation by the ovum is the main route of infection. The ova hatch into larvae that pass through the duodenal wall into either the portal vein or the periduodenal and perigastric lymphatics. The entry of the portal vein into the liver accounts for the predominance of cysts in this location. It is through this route that pulmonary cysts develop secondary to hepatic foci. Periduodenal and perigastric lymphatic channels, which connect with the thoracomediastinal lymphatics and thoracic duct, become infested, thus explaining the development of pulmonary lesions in the absence of hepatic cysts [l]. The lung is the second most common focus for this disease after the liver [2]. Inhalation of air carrying dried mi- From the Department of Thoracocardiac Surgery, First Teaching Hospital, Xinjiang Medical College, Uriimqi, Xinjiang Uighur Autonomous Region, The People's Republic of China. Presented at the International Conference on Thoracic and Cardiovascular Surgery, Beijing, China, Oct 28-30, 1986. Accepted for publication Apr 28, 1988. Address reprint requests to Dr. Qian, Department of Thoracocardiac Surgery, First Teaching Hospital, Xingjiang Medical College, No. 1 Xing Rd, Uriimqi, Xinjiang Uighur Autonomous Region, The People's Republic of China. crofragments of animal excreta that bear the ova can result in direct infection of the lungs [2]. The disease is endemic in certain areas of the world where sheepherding is a mainstay of existence, most notably, the Mediterranean, the Middle East, South America, Australia, and Central Asia. Urumqi is the capital city of an area comprising mainly dry, desertlike pastureland where nomadic tribes of sheepherders live. It lies on the western edge of China near the Soviet- Afghanistan border. The large numbers of sheep are supervised by herding dogs, the chief source of transmission of infection to the human population. Fifty-nine percent of all the cases of hydatid cyst in China have been reported from the Xinjiang region (W. J. Zhu, personal communication, 1986). Feng and colleagues [3] surveyed 4,633 persons in Xinjiang and found an infection rate of 7.8%. Material and Methods My first operation on a patient with thoracic hydatid cyst was performed on October 14, 1955, soon after I arrived in Xinjiang from Shanghai. A 12-year-old girl had a 10- cm cyst on her left upper lung. The operation went smoothly; it was a puncture-aspiration endocystectomy, the traditional and routine method employed worldwide at that time. The patient did well; however, three important mistakes were made in her care: (1) capitonnage was not performed; (2) the bronchial openings were not sutured; and (3) a dangerous amount of formalin was injected into the cyst. In later operations it became apparent that these practices and oversights could result in complications and death. The First Teaching Hospital of Xinjiang Medical College admitted 379 patients with thoracic hydatid cysts between 1957 (when it was founded) and 1975. The patients represented ll different nationalities and most (73.1%) came from the pastural and agricultural areas of the region. Of these, 63.1% were male and 36.9% female, with ages ranging from 3 to 63 years. Through the end of 1985, the number of cysts diagnosed totaled 813; 29 more patients with so-called "liver-roof'' cysts were referred to the thoracic service. Of these, 807 were treated surgically and 35 refused operation. We divided our total patients into two groups: Group 1, whose operations were performed from 1957 through June, 1975, and Group 2, whose operations were performed between July, 1975, and the end of 1985. Table 1 shows a comparison of the two groups with regard to type of operation and operative mortality. The increase in patients seen from mid-1975 to 1985 is probably explainable by the vast difference in medical resources and personnel that have become available in 342 Ann Thorac Surg 46:342-346, Sep 1988. Copyright 0 1988 by The Society of Thoracic Surgeons

343 Qian: Thoracic Hydatid Cysts Table 1. Comparison of Two Groups Undergoing Procedures for Thoracic Hydatid Cyst Removal No. of Procedures (%)" Group 1: Group 2 Type of 1957-1975 1975-1985 Total Procedure (N = 347) (N = 460) (N = 807) Endocystectomy 353 (75) 445 (83) 798 (79) Lung resection 49 (10) 71 (13) 120 (12) Drainage and other procedures 69 (15) 23 (4) 92 (9) Total 471 (100) 539 (100) 1,010 (100) "Operative mortality in Group 1 was 3 (0.9%), in Group 2, 2 (0.4%), and in Groups 1 and 2, 5 (0.6%). Xinjiang. For example, in the entire Xinjiang region, with a population of 5 million, there were 348 healthcare workers in the early 1950s. In 1984, with a population of 12 million, there were 68,337 people in healthcare positions, according to the National Health Bureau of the People's Republic. Diagnosis Symptoms in patients with hydatid cysts range from none or minimal to signs of significant compression, dramatic expectoration of cystic fluid or cystic membrane, or secondary infection. Cough, fever, night sweats, dyspnea, and chest pain are common in patients with large cysts or with complications. The chest roentgenogram is very important in the diagnosis of hydatid cysts. On radiographs, the cysts appear as round, homogeneous, well-defined densities with a diameter ranging from 2 or 3 cm to 18 cm; an average size of 8.3 cm was measured on the films of 260 cysts in 194 randomly selected patients (Fig 1). At our center we prefer to administer simultaneous, multiple, immunological tests for the diagnosis of hydatid cysts. Our recent research has demonstrated that immunodiagnosis with the avidin-biotinlhorseradish peroxidase compledenzyme-linked immunosorbent assay yields a 94.1% sensitivity; the enzyme-linked immunosorbent assay, an 81.2% sensitivity; the indirect hemagglutination test, an 87.1% sensitivity; the counterimmunoelectrophoresis test, a 71.2% sensitivity; and the Casoni skin test, an 87.5% sensitivity. The Casoni skin test has yielded false-positive rates as high as 37.5% in our experience. All of the other tests were 94.1 to 100% specific. In a series of 229 cases, 88.2% were diagnosed by A- mode sonography, which can easily differentiate cystic lesions from solid ones [4]. B-mode sonography probably would be more illustrative, but has not been used routinely at our center. Classification of Cysts We have devised a clinical classification scheme for thoracic hydatid cysts. Except for 2 patients with cardiac Fig 1. Preoperative chest roentgenogram of hydatid cyst in right lower lobe of a 42-year-old man. cysts [5] and 1 with a chest wall cyst, our patients fell into four categories: TYPE 1. The simple, intrapulmonary cyst, which shows no pleural or mediastinal involvement and is neither infected nor ruptured. In our entire series, 423 (50.2%) patients fell into this category. This is the ideal indication for endocystectomy, especially intact endocystectomy. TYPE 2. The complicated intrathoracic cyst that is ruptured or infected, that may involve the pleura or mediastinum, and that may or may not be complicated by empyema or bronchiectasis. Three hundred fifty-six patients (42.3%) fell into this category. In addition to excision of the cyst, some kind of lung resectional therapy usually was indicated, although a few individuals may escape with only mild infection in the lung tissue and thus are eligible for endocystectomy alone. TYPE 3. The thoracoabdominal cyst, which originates from an infected hepatic cyst. The diaphragm is penetrated by the infection, and there is communication between the infected hepatic cavity and the bronchi, forming a bronchohepatobiliary fistula. A small number of our patients (31 [3.7%]) were in this category. The infected hepatic cavity must be drained through an extrapleural, extraperitoneal route [6, 71. If a complicating empyema exists, separate drainage is necessary. TYPE 4. The infradiaphragmatic or "liver-roof'' type, which is a hepatic lesion without penetration of the diaphragm. Preoperatively, these cysts are difficult to differentiate from intrathoracic cysts. Surgically they should be approached through the thoracic cavity and resected in a fashion similar to that used for a cardial

344 The Annals of Thoracic Surgery Vol 46 No 3 September 1988 Table 2. Various Procedures Performed in 1,010 Operations for Thoracic Hydatid Cysts Operative Procedures No. of Operations Endocystectomy Pulmonary endocystectomy 707 Transthoraac hepatic endocystectomy 82 Myocardial or pericardial endocystectomy 2 Endocystectomy of thoracic wall 6 Endocystectomy of diaphragm Pulmonary resection Lobectomy Wedge resection Segmental resection Total pneumonectomy Drainage and other procedures Thoracostomy Subdiaphragmatic drainage Drainage of hydatid cyst Other operations Total 1,010 1 798 (79%) 83 20 16 1 120 (12%) 25 20 16 31 92 (9%) carcinoma of the stomach. Twenty-nine (3.4%) of the patients had this type of lesion. The various procedures performed are detailed in Table 2. Intact Endocystectomy Method In the earlier period (1957 through June 1975, Group l), endocystectomy was used less often than lung resection. Of 471 surgical procedures, 106 (23%) were intact endocystectomies. Over the years, as we gained skill with the technique of intact endocystectomy, we began to use it more frequently. In the later period (July 1975 through 1985), we performed 168 (31%) intact endocystectomies in a series of 539 procedures. The majar goal in treating a thoracic hydatid cyst is extirpation of the endocyst. The surgeon must remember that the elastic, ball-like endocyst is a living parasite that is continually growing, with the fluid it contains steadily increasing. A less flexible ectocyst surrounds the endocyst and restricts the parasite s growth from the outside. Thus, the cyst is always under tension like the bladder inside a football pressing against the rigid outer covering. The endocyst is made of noncellular chitin and is friable and easily torn. Therefore, it is essential to protect the operating field from spillage of cystic fluid, which contains the living protoscoleces. In earlier days, we injected formalin into the endocystic cavity in an attempt to kill the protoscoleces. Unfortunately this resulted in complications and a death because the formalin-cyst fluid leaked into the ectocystic cavity where several bronchial openings lay. Aspiration of the toxic fluid into the bronchial tree occurred. We no longer use formalin and are very careful to suture these bronchial apertures to avoid secondary infection. General anesthesia with intratracheal intubation should be used. Surgical exposure must be wide. Saline pads are packed beneath the lung, elevating it to a fixed position. The exposed portion of the cyst is whitish gray. Incision of the ectocyst must be done carefully and gently with the scalpel held at a 30-degree inclined angle. It may take several attempts to achieve the right plane of incision. Alternatively, one may use the scalpel or a mosquito clamp to catch the edge of the ectocyst s outer shell to tear it away. When the correct depth of incision has been made, the whitish endocyst will protrude from the incision and the outside pressure will decrease abruptly. This is the point at which cyst rupture is most likely to occur (Fig 2). The anesthesiologist is asked to stop respiratory motion while the surgeon quickly widens the incision to the same dimensions as the diameter of the endocyst. Next, the anesthesiologist increases intrapulmonary pressure to expand the lung, and the endocyst can be delivered intact. Two suction tubes should be kept ready during manipulation of the cyst in case of sudden rupture. The bronchial openings will begin to leak, which can result in anoxia and is especially dangerous for children. Therefore, these openings must be closed immediately with fine suture material or packed with gauze temporarily if there is a large leak. Capitonnage is done with fine sutures after the ectocyst is trimmed. Opposing surfaces are approximated face-to-face in multiple sutured rows to eliminate dead space. Purse-string sutures should be avoided since they may kink the neighboring bronchi and lead to atelectasis. With the goal of preserving maximum functioning lung tissue, one should realize that the ectocyst is not parasitic and does not need to be removed in its entirety. It includes surrounding lung tissue, which is atelectatic from compression, but often not infected. Once the endocyst is gone, this portion of lung usually reexpands very well. An alternative to the intact endocystectomy is aspiration of the endocyst prior to its removal. This makes removal of the crumpled endocyst easier, but sometimes results in recurrence a few years later because spillage of the parasite-containing fluid recontaminates the area. Results In the total series of 1,010 operations (807 patients) there were 5 operative deaths, for an operative mortality of 0.6% (see Table 1). Follow-up records are far from complete because the vast majority of our patients (96.5%) were herdsmen living far from Uriimqi and leading nomadic lives. For these reasons and for others related to economic and political changes occurring in the region in the past 10 years, we were unable to conduct follow-up studies after 1975.

345 Qian: Thoracic Hydatid Cysts Fig 2. Operative technique for intact endocystectomy. (A) Thoracic incision. (B) Operative field is carefully walled off and incision of ectocyst perfarmed with scalpel held at a 30-degree angle. (C) lncision into ectocyst is extended to diameter offull cyst to allow delivery. (D, E) Space occupied by cyst is carefully obliterated and all bronchial openings sutured. In the earlier series, 1957 through 1975, of the patients treated surgically, 323 were followed by periodic chest roentgenography for periods ranging from 3 to 20 years (71.8% were followed for more than 5 years). Among the 323 patients, 14 died-3 from hepatic hydatid cysts; 2 each from trauma, empyema, and cancer; and 1 each from encephalitis, pulmonary tuberculosis, alcohol poisoning, and perforation of gastric ulcer. In 1 patient the cause of death was unknown. Forty-six of the 309 survivors had varying degrees of cough, hemoptysis, expectoration, chest pain, and dys- pnea. These included 4 patients with pulmonary tuberculosis, 3 with pulmonary emphysema, 1 with chronic bronchitis, and 1 with right ventricular hypertrophy. Twenty-three patients had hemoptysis; 5 of these produced up to 100 ml of frank blood and 18 had bloodtinged sputum only. The majority of these patients have returned to work and active lives. We saw 32 patients in Group 1 who initially refused to undergo operation. Five of these were lost to follow-up and 6 died of hydatid cyst, surviving an average of 2.9 years after discharge. Of the 21 remaining patients, 9 were found to be free of cysts by roentgenographic examination after some years of follow-up. They had all repeatedly expectorated fragments of hydatid cyst or its membranous debris. There were no recurrences within an average of 3.9 years after full expectoration. We regard these patients as spontaneously cured.

346 The Annals of Thoracic Surgery Vol 46 No 3 September 1988 Five of the final 12 remaining patients eventually came back for operation, including 1 with a pericardial hydatid cyst. The 7 others who did not undergo operation had survived an average of 8.1 years at the time the follow-up study ended. We were able to follow 106 patients undergoing intact endocystectomy before July, 1975, for an average of 5.5 years. Two (1.9%) had recurrence in the same hemithorax where the original cyst appeared. Reoperation was performed and the cysts delivered intact. Two more patients had cyst reappearances, one in the contralateral lung and one in the sacrospinalis muscles. We do not believe these were recurrences but rather new infections or cysts that were small enough to evade detection at the first operation. Of 136 patients undergoing aspiration and followed for the same time period, 3.7% had recurrences. We believe that the results with the two techniques are nearly comparable. Comment The first 30 cases of hydatidosis in China were collected and reported by Locks [8] in 1930. No case was reported in Xinjiang until 1955, but by 1981 the Xinjiang Branch of the Surgical Society of the Chinese Medical Association had collected 5,755 surgically treated cases, still an incomplete statistical figure. This is not to imply that the disease has been spreading widely and rapidly in China, but rather that there has been great improvement in treating and documenting medical cases in the last 30 years. Prevention of hydatidosis is as important as treatment in areas such as Xinjiang, where the disease is endemic. Surveillance systems and preventive regulations need to be established and enforced. To the degree possible, considering the nature of the population, hygienic conditions should be strongly encouraged. Animals can be treated with the praziquantel [9] or bunamidine hydrochloride, or both, to reduce the danger of transmission of the parasities. Operation is the treatment of choice for pulmonary hydatid cysts. In at least half of the patients, Barrett's technique of intact endocystectomy can be used to excise the cyst. In 1949 Barrett [lo] initially reported 4 cases of successful delivery of an intact endocyst with a followup report by Barrett and Thomas in 1952 [ll]. The technique became obsolete, however, until 1972, when Xanthakis and colleagues [12] reported 29 attempts at intact endocystectomy with 6 failures, and Lichter [13] also reported his experience with the procedure. We have used this technique since 1959 and have been able to report increasingly good results [14-161. Of 14 operations attempted in the early period, the cyst was ruptured during operative manipulation in 6 (42.9%). Thirty-five ruptures occurred in 106 operations carried out before July, 1975. From 1975 to 1985, there were 18 ruptures among 168 cases. We began with small cysts and as our skill increased attempted larger ones. In 1975 the biggest cyst encountered in our entire series, measuring 18 cm in diameter and weighing 3,200 gm, was removed by intact endocystectomy. The immediate and late results of endocystectomy by either the intact or aspiration method were excellent. The technique is safe and simple, and allows maximal preservation of lung tissue. Intact delivery of the cyst is the ideal method. One need not fear sudden rupture if the operating field is carefully protected. Recurrence rates are nearly equal among patients undergoing intact and aspiration endocystectomy. I thank Dr. Herbert Sloan, Section of Thoracic Surgery, Department of Surgery, The University of Michigan, Ann Arbor, for his help in the preparation and editing of this article and for his encouragement to submit the manuscript. I also thank the members of my staff who assisted with this work throughout the years. References 1. Sarsam A: Surgery of pulmonary hydatid cysts: review of 155 cases. J Thorac Cardiovasc Surg 62663, 1971 2. Aydin A, Yurdakul Y, Ikizler C, et al: Pulmonary hydatid disease: report of 100 patients. Ann Thorac Surg 23:145, 1977 3. Feng XH, Zhao RQ, Lu XH, et al: Hydatid cyst infection among the habitants of North Xinjiang. Acta Acad Med Xinjiang 9278, 1986 4. Ying SY, Liu TF, Zhang ZL, et al: Preliminary report of ultrasonic diagnosis on pulmonary hydatid cyst. Acta Acad Med Xingjiang 2143, 1983 5. Qian ZX, Qiao J, Wu MB, et al: Hydatid cyst of the heart: report of 2 cases. Chin J Surg 21:640, 1983 6. Qian W, Zhao XY: Surgical treatment of 690 thoracic cases of hydatid cysts. Chin J Thorac Cardiovasc Surg 1:41, 1985 7. Qian W: Surgical treatment of hydatid cysts of the chest. In Wu YK, Peters RM (eds). International Practice in Cardiothoracic Surgery. Beijing: Science Press, 1985, 419-423 8. Locks HH: Hydatid-a review and a report of cases from North China. Chin Med J 16:402, 1930 9. Pearson RD, Guerrant RI: Praziquantel: a major advance in antihelminthic therapy. Ann Intern Med 99:195, 1983 10. Barrett NR: Pulmonary hydatid cysts. Removal of simple univesicular pulmonary hydatid cyst. Lancet 2234, 1949 11. Barrett NR, Thomas D: Pulmonary hydatid disease. Br J Surg 40:222, 1952 12. Xanthakis D, Efthimiadis M, Papadakis G, et al: Hydatid disease of the chest. Report of 91 patients surgically treated. Thorax 1972;207517 13. Lichter I: Surgery of pulmonary hydatid cyst-the Barrett technique. Thorax 27529, 1972 14. Qian ZX, Tang GX, Liu RL, et al: Intrathoraac echinococcosis and its operative treatment. Chin J Surg 14:91, 1966 15. Qian W, Guo SY, Tang GX, et al: Immediate and long-term results of surgical treatment of intrathoracic hydatid cysts. Chin Med J 93:569, 1980 16. Qian ZX, Guo SY, Tang GX, et al: Evaluation of Barrett's technique in 67 cases of pulmonary hydatid cyst. Chin Med J 93:577, 1980