World J. Surg. 19, 714-719, 1995

WORLD Journal of

SURGERY �9 1995 by the Soci6t6

Internationale de Chirurgie

Diaphragmatic or Transdiaphragmatic Thoracic Involvement in Hepatic Hydatid Disease: Surgical Trends and Classification

Ramon G6mez, M.D., Ph.D., Enrique Moreno, M.D., Ph.D., Carmelo Loinaz, M.D., Ph.D., Angel De la Calle, M.D., Camilo Castellon, M.D., Marina Manzanera, M.D,, Vicente Herrera, M.D., Arturo Garcia, M.D., Manuel Hidalgo, M.D., Ph.D.

General and Digestive Surgery, Liver Transplant Unit, "12 de Octubre" University Hospital, Carretera de Andalucfa Km 5400, 28041 Madrid, Spain

Abstract. We performed a retrospective study of 19 patients who had been operated on for hepatic hydatid disease with diaphragmatic or transdia- phragmatic (D-TD) thoracic involvement chosen from a total of 444 patients who underwent operations for hepatic hydatid disease. In all cases D-TD involvement was confirmed by ultrasonography, CT, or MRI scan. We propose a new classification (grades 1-5) based on the degree of development of D-TD involvement. Before 1984 exposure was obtained by thoracophrenolaparotomy (nine cases) and later~ by right subcostal incision. Only four patients required atypical pulmonary resection. In 13 cases the diaphragm was repaired, and all 24 hepatic cysts were treated with total (16 cases) or partial (8 cases) cystopericystectomy. There was no operative mortality, and the most serious morbidity consisted of a biliary fistula and a biliobronchial fistula. For treatment of these patients we recommended right subcostal incision and total or near-total cys- topericystectomy as a first choice of surgical technique.

The major characteristic of parasitic infestation by Echinococcus granulosus in humans is the appearance of cysts located mainly, though not exclusively, in the liver [1, 2]. The invasion of the thoracic cavity by cysts located in the hepatic dome is a serious but infrequent complication [3-5]. Thoracodiaphragmatic involve- ment and the proximity of the cysts to the hepatic veins or the inferior vena cava call for high risk surgery [4]. Thoracic or thoracolaparotomy incision [4-9] and simple drainage of the hepatic cysts [5-7] formerly generally recommended for the treatment of hydatid cysts [1]. However, nowadays an exclusively abdominal approach (right subcostal incision) with removal of all or almost all the pericyst membrane of the hepatic cysts by closed or open technique can be recommended. Our experience in the treatment of hepatic hydatid cysts with diaphragmatic or trans- diaphragmatic thoracic involvement (D-TD) is based on almost 20 years' experience with hydatid disease. We propose a simple Classification of these cysts and describe some changes in our surgical viewpoint.

Correspondence to: R. G6mez, M.D., Ph.D. at present address c/n Isabel Tintero, 1-3 ~ A, 28005 Madrid, Spain.

Material and Methods

Patients

From 1974 to December 1994 we treated 450 patients with abdominal hydatid disease. In 444 patients the disease was located in the liver, and in 6 there was an extrahepatic abdominal localization (1.3%). Among the 444 patients with hepatic hydatid disease, 19 patients (12 male, 6 female) (4.2%) were selected for a retrospective study, all of whom had diaphragmatic or thoracic involvement secondary to hepatic hydatid cysts.

The mean age of these patients was 46.2 years (range 21-73 years). Four patients had undergone a previous surgery due to hepatic hydatid disease (patients 3, 12, 16, 18) at 2, 11, 38, and 20 years before. The most frequent symptom was abdominal pain located in the upper right abdominal region (16 patients), fol- lowed by fever (6 patients), jaundice (5 patients), recurrent bronchitis with coughing and expectoration (4 patients), and vomiting (2 patients). One presented in anaphylactic shock (rash, pruritus, fever, and arterial hypotension). In every case serologic techniques (Casoni's test, immunofluorescence), an eosinophil count in peripheral blood, and a thoracic and abdominal radio- graph were used to diagnose hepatic hydatid disease. In the early patients liver scintigraphy (HIDA) (7 patients) and laparoscopy (3 patients) were used. Ultrasonography (14 patients) and thoraco- abdominal CT scans (9 patients) have been mainly used during the last 10 years. MRI was used on patient 15. For preoperative confirmation of D-TD involvement, plain posteroanterior and lateral thorax radiographs (Fig. 1), ultrasonography, CT scans (Fig. 2), and recently MRI (Fig. 3) were used. When bronchial involvement was suspected, bronchography was performed. Table 1 outlines the size and number of hepatic cysts and their topo- graphic location, using Couinaud's segmental classification [10].

Classification of Diaphragmatic and Transdiaphragmatic Thoracic Involvement

The patients were classified in five grades (Fig. 4) according to the degree of evolution of the diaphragmatic or thoracic (pleuropul-

G6mez et al.: Hepatic Hydatidosis 715

Fig. 1. Radiograph of thorax (patient 15) showing elevation of the right diaphragm caused by an enormous hydatid cyst in the hepatic dome affecting the middle and lower lobe of the lung.

monary) involvement. Grade 1 (adhered cyst): There are firm adherences between the surface of the cyst and the diaphragm but no diaphragmatic perforation. In some cases it was possible to obtain a separation plane between the cyst and the diaphragm. Grade 2 (hydatidic transit): Cyst perforates the diaphragm, but there is little invasion of the thoracic cavity. The diaphragmatic defect needs repair. Grade 3 (pleurothoracic vesiculation--cyst in "sandglass"): Cyst perforates the diaphragm and either grows inside the thoracic cavity or daughter vesicles become established. Grade 4 (disease of the pulmonary parenchyma): Cyst connects to the bronchial branches, or there is simply compression and atelectasis of the pulmonary parenchyma. Grade 5 (chronic bron- chial fistula): This stage is the chronic aftermath stage, either postoperative or as a result of the spontaneous evolution of hydatid disease.

Surgical Technique

Before 1984 exposure was obtained by thoracophrenolaparotomy (9 patients) and afterward through a right subcostal incision widened to the left midclavicular line (last 10 patients) (Table 1).

Hepatic Cysts

The technical details of each surgical method have already been described [1, 2]. Total closed or total open cystopericystectomy technique (TCC or TOC) was chosen. Whenever a partial open technique (POC) was performed, as much of the pericyst mem- brane as possible was removed. Exploration of the bile duct depended on preoperative findings (cholecholedocholithiasis, jaundice) and on whether the surgeon suspected that hydatids had passed into the bile duct or that there had been biliary fistula.

Fig. 2. CT scan of patient 15. A. Hydatid cyst occupies the whole dome of the right hepatic lobe. Note the hydatid membrane on the inside of the cyst. B. Thoracic section showing diaphragmatic perforation with involve- ment of the adjacent pulmonary parenchyma. Atypical pulmonary resec- tion was necessary.

Diaphragmatic and Pleuropulmonary Involvement

At Grade i it was usually possible to dissect the adherences of the cyst to the diaphragm and so fully conserve the latter. Defects of the diaphragm (grades 2-4 and some of grade 1) were repaired with either continuous or interrupted sutures using nonresorbable material. The daughter vesicles established in the pleural cavity were all removed by total closed or open cystectomy. In the event of pulmonary parenchyma involvement (grade 4), atypical resec- tion of the affected parenchyma adherent to the cyst was per- formed. Thoracic drainage tubes were placed if the thoracic cavity had to be opened (via the incision itself or by aperture of the diaphragm). Abdominal drainage was performed in all cases.

Results

Treatment of Hepatic Hydatid Cysts

A total of 24 cysts were treated in 19 patients. The patient with grade 5 pleuropulmonary involvement had a fibrotic reaction in

716 World J. Surg. Vol. 19, No. 5, Sept./Oct. 1995

Fig. 3. MRI scans of patient 15. Anteroposterior view (A) and lateral view (B) showing the topography of the hydatid cyst in relation to the thoracic organs. A "daughter" vesicle is located in the posterior costo- phrenic vertebral space (grade 4).

the region of the previous surgery. Of the 18 active cysts, 17 (94.4%) were located in segments VII and VIII (hepatic dome). POC was performed on 8 cysts, TOC on 4, and TCC on 12. Cholecystectomy was performed on 11 patients (57.9%) (for transcystic cholangiography in 6 cases, gallbladder lithiasis in 3, and gallbladder involvement in 2). In 6 cases (31.5%) the bile duct was decompressed by sphincteroplasty of the Vater's ampulla (two patients with multiple choledocholithiasis and two due to connection of the cyst to the bile duct) or by placing a T-tube (one per daughter vesicle in the choledochus and another because of biliary leakage on the bleeding surface of the liver).

Treatment of Diaphragmatic and Pleuropulmonary Involvement

Table 1 shows the treatment in each case. For five cases of grade 1, the cyst was separated (dissection) from the diaphragm; in the remainder (4 cases), resection of the part of the diaphragm joined to the cyst was necessary. In the latter cases and grades 2 to 4, the diaphragmatic defects needed repairing. In two of the five grade 3 and 4 cases, the cysts were separated from their connection to the pleura and to the pulmonary parenchyma, and resection was not necessary; in the 3 remaining cases, however, atypical resec- tion of pulmonary parenchyma involvement by the cyst was necessary. Patient 19 had undergone previous surgery (20 years ago) for hepatic hydatid disease, when right hepatic resection and cystectomy was performed. This patient had since had an external biliary fistula, which with the passing of time and because of recurrent subphrenic abscess had developed into a biliobronchial fistula (grade 5). In this case the biliobronchial fistula between an area of fibrotic reaction of the hepatic surface and the middle right lobe of the lung was identified and resected. The diaphrag- matic defect was not repaired because fibrosis prevented the edges from being brought together; consequently, an epiploplasty between the liver and the thoracic cavity blocked by fibrosis was performed.

There were no complications resulting from aperture and subsequent repair of the diaphragm in the cases described.

Hydatid Cyst Recurrence

After a mean 8.3-year follow-up (range 3 months to 17 years), only one hepatic hydatid cyst recurrence measuring 4 • 5 cm was detected (patient 7) in the right hepatic lobe 5 years after surgery (a TOC was performed). The patient is being monitored with regular liver ultrasonography, and the size of the cyst has not altered throughout postoperative follow-up. No new cysts local- ized in the thorax have been detected.

Morbidity

Table 2 shows the complications in eight patients. In two patients the external biliary fistula cleared spontaneously, whereas in another surgery was necessary. Surgery was eventually performed on the patient with long-term evolution of the biliobronchial fistula.

Mortality

There was no hospital mortality (first 30 days), although two patients died during follow-up. One of the patients with a year-long evolution of chronic external biliary fistula (which was not resolved by surgical sphincteroplasty of Vater's ampulla) was treated with right hepatic resection and died from hepatic failure during the postoperative period. The resected liver showed granulomatosis, obstruction of large bile ducts, cholangitis, and acute/chronic portal infiltration. The second patient who died had a chronic biliobronchial fistula that was treated a year later by sphincteroplasty of Vater's ampulla. However, the persistence of the fistula 18 months after sphincteroplasty made it necessary to perform another thoracophrenolaparotomy for resection of two segments of the lower right pulmonary lobe. The patient died from sepsis on postoperative day 6.

G6mez et al.: Hepatic Hydatidosis 717

Table 1. Characteristics of the cysts: classification and surgical treatment.

Treatment

No. Size Classification Surgical Hydatic Pt. H-Cy Site (cm) (1-5) approach/year cyst Diaphragm Lung

1 2 VII, VIII 10 • 12 1 TP/77 PO Dissection IV, V 5 • 8 - - PO

2 2 VIII 6 • 6 1 TP/78 TO Resection II, III 5 • 6 TC

3 1 VI, VII 5 • 8 1 TP/80 TC Resection 4 1 IV-VIII 12 • 20 1 TP/81 PO Resection 5 1 IV-VIII 20 • 15 1 SC/88 PO Dissection 6 2 V-VIII 12 • 12 1 SC/88 PO Dissection

III 6 • 6 TC 7 1 VII, VIII 8 • 6 1 SC/91 TC Resection 8 1 V-VIII 12 • 20 1 SC/93 TO Dissection 9 1 VIII 7 • 7 2 TP/77 PO Resection 10 2 VII, VIII 6 • 7 1 SC/82 PO Resection

IV 6 • 6 2 TC 11 1 VI-VIII 18 • 15 2 SC/88 TC Resection 12 1 IV, V-VIII 8 • 8 2 SC/91 TC Resection 13 1 V-VIII 15 • 12 2 SC/92 TO Resection 14 1 VII 7 • 10 3 TP/78 TO Resection 15 1 V-VIII 16 • 22 3 TP/84 TC Resection 16 2 IV-VIII 5 • 7 4 TP/74 TC Resection

V 4 x 3 - - TC 17 2 VIII 10 • 10 4 TP/80 TC Resection

V 9 • 9 TC 18 1 IV, V, VII, VIII 15 • 20 4 SC/93 PO Resection 19 1 III - - 5 SC/93 - - Resection

Dissection Dissection Resection

Resection

Resection Resection

No H-Cy: number of hydatid cysts; Site: topographic location in liver, using Couinaud's segmental classification; TP: thoracophrenolaparotomy; SC: subcostal laparotomy; TC: total closed cystopericystectomy; TO: total open cystopericystectomy; PO: partial open cystopericystectomy.

b , - i

I I ~ l l n ' n l I i q n I i n i �9 I 0

I

b

I F F

Fig. 4. Classification of patients with hydatid cysts in the hepatic dome based on the type of diaphragmatic and thoracic involvement (explained in text).

Discussion

Diaphragmatic or transdiaphragmatic (pleuropulmonary) tho- racic involvement by hydatid cysts in the hepatic dome ranges from 0.6% to 16.0% of all cases of hepatic hydatid disease [3, 5, 6, 9, 11-13]. The progressive growth of the cysts, their tendency to erode the organs and tissues with which they come into contact, their infection, and the existence of negative intrathoracic pres- sures could explain the unusual evolution of some of the cysts located in the hepatic dome [8, 9, 11]. The damaging effect of the

Table 2. Postoperative complications.

Classification Type of Pt. (grades 1-5) Incision Complication Evolution

i 1 TP Biliobronchial Reintervention, died fistula

4 1 TP Biliary fistula Reintervention, died 5 1 SC Biliary fistula Satisfactory 6 1 SC Right neumonia Satisfactory 7 1 SC Biliary fistula Satisfactory

10 1-2 SC Right subphrenic Reintervention, abscess satisfactory

15 3 TP Right pleural Satisfactory effusion

18 4 SC Right pleural Satisfactory effusion

See Table 1 for abbreviations.

cyst on the diaphragm progresses with time, developing from mere adherence to perforation. Once the cyst crosses the dia- phragm there is a possibility of: (1) its vesiculation in the thoracic cavity; (2) implantation of new daughter vesicles in the pleural cavity; (3) the cyst rupturing into this cavity; or less commonly (4) affectation of the pulmonary parenchyma and connection of the cyst to the bronchial branches [5-9, 12, 14]. Several classifications may be applied to this type of cyst depending on the degree of diaphragmatic or thoracic involvement, ranging from elementary to highly complex [3-5, 9]. The classification we propose adjusts well to the characteristics of the cases we have treated; it is both simple and contains aspects of the classifications proposed by Kilani et al. [3], Freixenet et al. [4], and Yuste et al. [5]. Patients '

718 World J. Surg. Vol. 19, No. 5, Sept./Oct. 1995

classification in each of the five grades we propose can be established preoperatively and may influence the method of exposure, surgical approach, and the risk rate of the operation.

Diagnosis of hepatic hydatid disease has changed as a result of technologic innovations. At present it is based on ultrasonogra- phy, CT scans, and more recently MRI [11]. Techniques such as laparoscopy, liver scintigraphy, and even serologic tests have taken a secondary place. Suspicion of diaphragmatic or pleuro- pulmonary involvement can be initiated by simple chest radiog- raphy and is confirmed with CT or MRI [11].

Some aspects of the surgical techniques for treating these patients have changed during the last 10 years and should be mentioned. Because of the proximity of these cysts to the inferior vena cava and hepatic veins and the possible thoracic involvement [6, 8] (which often meant that these patients were treated by thoracic surgeons) [3, 4, 8], for decades wide exposure of the area was obtained by thoracotomy or thoracophrenolaparotomy [4-7, 9, 11, 12]. However, for many years our group has chosen a wide right subcostal incision for surgical exposure of patients with hydatid cysts and D-TD involvement. This exposure has been used routinely for the patients we have operated on since 1984. Its justification is based on the facts that: (1) subcostal incision provides adequate exposure and the possibility of liberating the liver, allowing more complete removal of the hepatic cysts (total open or closed cystopericystectomy); (2) it makes exploration of the bile duct easier; (3) if required, cyst adherences to the pulmonary parenchyma can be either dissected or atypically resected through a diaphragmatic aperture; and (4) increased morbidity from thoracophrenolaparotomy is avoided. In the same way, Moumen and El Fares [14], Warren et al. [15], and Marcote [16] have stated their preference for the abdominal approach for resolving biliobronchial fistular pathology (including pulmonary resection). Although Yuste et al. [5] recommended thoracotomy, their cases were treated in relation to pulmonary involvement. Fortunately, nowadays the diagnosis and treatment of these patients can be performed in early stages; hence a subcostal laparotomy could be enough, as suggested by Marcote [16]. Thoracotomy or thoracophrenolaparotomy could be indicated in the event of the coexistence of hepatic hydatid disease and thoracic and pulmonary hydatid involvement in other segments. However, the choice of one route of exposure or another often depends on the speciality of the surgeon (general and digestive or thoracic) who is treating the patient [15].

We believe that greater consideration should be given to total cystectomy as the ideal technique for the treatment of hydatid cysts. Although total closed cystectomy can be performed on many patients with D-TD involvement [1], when the size of the cyst prevents adequate control of the hepatic veins or inferior vena cava [6, 7] open technique should be used. In the event of partial cystectomy, resection of the pericyst membrane should be per- formed as widely as possible and should not be confined to the aperture and drainage of the cavity, as others have proposed [6, 7, 11]. This approach reduces morbidity and the postoperative hospital stay and can be performed easily with modern elec- troscalpels [1]. For treatment of diaphragmatic involvement, it is important to perform blunt dissection of the greater part of the diaphragm adhering to the cyst. This technique reduces the diaphragmatic defect, and a separation plane can often be achieved, thereby avoiding the need to resect part of the dia- phragm (grade 1). Diaphragmatic defects can easily be repaired

and present no problems during follow-up. In only one of the cases mentioned was it impossible to repair the diaphragm because of the fibrosis caused by the chronic biliobronchial fistula.

Our long-term results in the treatment of complex hydatid disease in patients with diaphragmatic or pleuropulmonary in- volvement have been satisfactory. In this sense, the key to correct treatment is adequate exposure through a wide right subcostal incision and performance of total or near-total open cystopericys- tectomy techniques for cysts that are difficult to dissect because they are connected to the hepatic veins or to the inferior vena cava.

R6sum6

Nous avons 6tudi6 r6trospectivement 19 patients op6r6s pour une hydaditose h6patique s'6tendant soit vers le diaphragme, soit vers le thorax par extension transdiaphragmatique (TD) dans une s6rie de 444 patients ayant 6t6 op6r6s. Dans tousles cas de TD, le diagnostic a 6t6 confirm6 par l'6chographie, la tomodensitomdtrie ou la r6sonance magn6tique nucl6aire. Nous proposons une nouvelle classification (grades 1 ~ 5), bas6e sur le degr6 de TD. Avant 1984, une thoracophr6nolaparotomie a 6t6 la voie d'abord prdfdrde (9 cas) puis on a utilis6 la voie souscostale droite. Seulement quatre patients ont n6cessit6 une rdsection pulmonaire atypique. Chez 13 patients, on a rdpar6 imm6diatement le dia- phragme et tousles kystes hydatiques h6patiques (n = 24) ont 6t6 trait6s par une p6rikystectomie soit totale (16 cas) soit partielle (8 cas). I1 n'y a eu aucun d6c6s et la complication la plus grave observ6e a 6t6 une fistule biliaire et bilio-bronchique. Nous recommandons la p6rikystectomie totale ou presque totale par une incision sous-costale droite prolong6e chez ces patients.

Resumen

Hemos realizado un estudio retrospectivo de 19 pacientes opera- dos por enfermedad hidatfdica hepfitica con extensidn diafrag- mfitica o transdiafragmfitica (E-TD) al torAx, dentro de un total de 44 pacientes sometidos a cirugfa pot enfermedad hidatfdica del hfgado. En la totalidad de los casos la extensi6n E-TD rue confirmada por ultrasonograffa, TAC o resonancia magn6tica. Proponemos una nueva clasificaci6n (grados 1 a 5) basada en el grado de desarrollo de la extensi6n E-TD. Con anterioridad a 1984, se hizo la exposici6n mediante toracofrenolaparotomfa (9 casos) y m~is tarde por incisi6n subcostal derecha. $61o 4 pacientes requirieron una resecci6n pulmonar atfpica. En 13 casos el diafragma fue reparado y todos los 24 quistes hepfiticos fueron tratados mediante cistopericistectomfa total (16 casos) o parcial (8 casos). No se registr6 mortalidad operatoria y la morbilidad mgs seria consisti6 en una fistula biliar y una broncobiliar. Para el tratamiento de este tipo de pacientes nosotros recomendamos una incisi6n subcostal derecha y una cistopericistectomfa total o casi total como la t6cnica quirfirgica de primera escogencia.

References

1. Moreno, E., Rico, P., Bercedo, J., Garcia, I., Palma, F., Hidalgo, M.: Results of surgical treatment of hepatic hydatidosis: current therapeu- tic modifications. World J. Surg. 15:254, 1991

2. G6mez, R., Marcello, M., Moreno, E., et al.: Incidencia y tratamiento

G6mez et al.: Hepatic Hydatidosis 719

quirurgico de la hidatid0sis abdominal extrahepatica. Rev. Esp. Enf. Dig. 82:100, 1992

3. Kilani, T., Dauoes, A., Horchani, H., Sellami, M.: Place de la thoracotomie darts les complications thoraciques des kystes hyda- tidiques du foie. Ann. Chir. 45:705, 1991

4. Freixinet, J.L., Mestres, C., Cugat, E., et al.: Hepatothoracic transdi- aphagmatic echinococcosis. Ann. Thoracic Surg. 45:426, 1988

5. Yuste, M.G., Duque, J.L., Heras, F., et al.: Evolution thoracique des kystes hydatiques du foie et ses complications. Ann. Chir. Thoracic Vasc. 38:153, 1984

6. Raventos, J., Nogueras, M., Riux, X., Lorenzo, T.: Hydatid disease of the liver with thoracic involvement. Surg. Gynecol. Obstet. 143:570, 1976

7. Yacoubian, H.D.: Thoracic problems associated with hydatic cyst of the dome of the liver. Surgery 79:544, 1976

8. Borrie, J., Shaw, J.H.: Hepatobronchial fistula caused by hydatid disease. Thorax 36:25, 1981

9. Miguelena, J.M., Guemes, A., Ramirez, J.M., et al.: Transitos hida- tidicos abdominotoracicos. Cir. Esp. 52:98, 1992

10. Couinaud, C.: Le Foie: Etudes Anatomiques et Chirurgicales. Mas- son, Paris, 1957

11. Grande, D., Ruiz, J.C., Elizagaray, E., Grande, J., Barcena, V., Eguidazu, J.: Hepatic echinococcosis complicated with transphrenic migration and bronchial fistula: CT demonstration. Gastrointest. Radiol. 15:115, 1990

12. Erguney, S., Torture, O., Haydar, A., Ertem, M., Gazioglu, E.: Les kystes hydatiques compliques du foie. Ann. Chir. 45:584, 1991

13. Goinard, P., Pegullo, J., Pellissier, G.: Le Kyste Hydatique, Thera- peutique Chirurgicale. Masson, Paris, 1960, pp. 81-88

14. Mdumen, M., E1 Fares, F.: Les fistules bilio-bronchiques d'origine hydatique: a propos de 8 cas. J. Chir. 128:188, 1991

15. Warren, K.W., Christophi, C., Armendariz, R., Basu, S.: Surgical treatment of bronchobiliary fistulas. Surg. Gynecol. Obstet. 157:351, 1983

Invited Commentary

Sergey V. Gothey, M.D.

Center of Surgery, Moscow, Russia

Diaphragmatic or transdiaphragmatic hydatid invasion from the liver is one of the most dangerous complications of generally benign parasitic disease. The rarity of diaphragm involvement, surgical techniques, and results presented are rather typical for hospitals with a large hydatid surgical experience in Europe. However, although the retrospective study of 444 cases of liver hydatidosis revealed only 19 patients with this complication, the precise analysis of each case is of great importance and interest.

Diaphragmatic and transdiaphragmatic invasions are more

frequent in eastern regions, including Russia, where the percent- age of these complications of liver hydatidosis reaches 12% to 16%. The authors' attempts to make the surgery more radical are quite natural. The surgical approaches they used were conven- tional for obtaining good conditions for surgery. It seems to us, however, that obligatory excision of diaphragmatic fragments to remove a part Of the fibrous pericyst membrane is not necessary, except in cases complicated by biliobronchial or cystobronchial fistulas. Such techniques avoid the need for diaphragmatic repair after subtotal pericystectomy. In some elderly and high risk patients surgery may be divided into two steps--peritoneal and pleural--to avoid the serious complications of a combined laparothoracotomy surgical incision. Intraoperative bile duct radiographic investigation and precise excision of cicatricial and calcified tissues are of great importance to prevent biliary and bronchial fistulas.