Introduction

Hydatid disease is a parasitic infection, relatively common in rural areas, caused by larvae of the parasite platyhelminth Echinococcus granulosus (dog tapeworm). Humans become affected from water, food, or direct contact with carnivores [₄]. The echinococcal cyst itself consists of a germinal layer and of cyst fluid containing brood capsules and scolices of the worm. The liver (60%) and lungs (20-30%) are the organs most frequently affected, however cysts can be found in nearly every organ [₁,₂]. An echinococcal cyst may lie dormant for many years and remain asymptomatic, still rupture can occur at any time and thus extend the disease [₃]. Intrathoracic rupture of a hepatic hydatid cyst has been reported and is a severe complication causing a spectrum of lesions [₄, ₅]. We report the unusual case of a patient who developed retroperitoneal and pararenal echinococcosis following rupture of a left pulmonary hydatid cyst into the pleural cavity and dissemination of pleural and extrapleural echinococcosis through perforation of the left hemidiaphragm. Our patient had no signs of hepatic disease.

Case Report

A 29-year-old non-smoker female, who migrated to Athens, was admitted to our hospital with left pleuritic pain. She had been hospitalized eight months earlier in her native country, for hydropneumothorax and empyema of the left hemithorax. At that time the patient, had been treated with tube thoracostomy and some antibiotics she could not specify. Physical examination revealed unilateral hypophonesis on chest auscultation and left subcostal pain on palpation. Chest roentgenogram showed multiple well-defined and homogeneous, spherical opacities of the left middle and lower pulmonary fields (fig. 1a). Lateral view (fig. 1b) demonstrated extrapulmonary location.

Figure 1

Figure 1a: Chest roentgenogram showing multiple well-defined and homogeneous, spherical opacities of the left middle and lower pulmonary fields.

Figure 2

Figure 1b: Chest roentgenogram, lateral view.

Arterial blood gas analysis and routine laboratory assessment were normal. White blood cell count was 8.1?103/?L, with 2% (relative) eosinophils. The titre of antiechinococcal antibodies was positive 1:2580 (ELISA, bioMérieux, titre of negative control <1:100). Evaluation with computed tomography (CT) defined size, number and position of the cysts. Multiple extrapulmonary located cysts were in contact with the posterior, mediastinal and diaphragmatic surface of the pleura (fig. 2). Others invaded the left diaphragm and extended to the posterior peritoneum and the upper pole of the left kidney (fig. 3).

Figure 3

Figure 2: CT-scan showing multiple extrapulmonary located cysts, adjacent to the posterior, mediastinal and diaphragmatic surface of the pleura.

Figure 4

Figure 3: CT-scan showing retroperitoneal and pararenal located cysts.

Disseminated echinococcosis, following spontaneous rupture of a pulmonary hydatid cyst into the pleural cavity, was diagnosed and the patient underwent surgical treatment.

Posterolateral thoracotomy through the sixth intercostal space was accomplished, with the patient in the lateral decubitus position. After the cysts were identified, they were surrounded by wet packs soaked in diluted povidone-iodine solution, to prevent local spread. For a better exploration of the posterior peritoneum an additional incision above the eleventh rib was performed. All cysts were removed intact, the diaphragm was repaired, while a wedge resection of the left lateral basal pulmonary segment was performed, as it was firmly attached to the pleura. The postoperative course was uneventful. The patient had an uncomplicated recovery and was discharged on the eighth postoperative day on a regimen of albendazol anthelmintic therapy, 800 mg/d for 3 cycles. She remains well and free of disease one year after surgical treatment. The titre of antiechinoccocal antibodies is negative and there is no sign of recurrence in the CT-scan.

Discussion

Pulmonary echinococcosis is caused by the small tapeworm Echinococcus granulosus, which spends part of its parasitic life cycle in dogs and sheep. It is endemic in many rural areas of the world and surgery remains the principal mode of treatment, as medical therapy alone is not sufficient [₁,₂,₃]. Immunologic tests and radiological imaging are usually adequate to establish the diagnosis [₆,₇,₈]. Surgical treatment consists of complete excision of the disease process, with maximum preservation of lung tissue [₁,₂]. In our case, patient's history, characteristic imaging and serologic test results (the titre of antiechinococcal antibodies was positive 1:2580, ELISA, bioMérieux, titre of negative control <1:100) led us to the conclusion, that the reported episode of hydropneumothorax and empyema eight months ago, was due to spontaneous rupture of a pulmonary echinococcal cyst into the pleural space. In addition the detailed preoperative topographic evaluation with CT scanning was essential in localizing the lesions and planning the surgical approach. The lung is the second most commonly affected organ after the liver (10-40%) [₁]. Nevertheless the absence of hepatic hydatid disease and the left sided location of the process in our patient were noteworthy.

We considered thoracotomy as the best approach for this patient, however an additional incision above the eleventh rib, proved to be necessary for complete removal of the retroperitoneal and pararenal cysts. The procedure of choice for removal of intact cysts is controversial. Needle aspiration versus enucleation is recommended by some surgeons [₂]. Special intraoperative precautions must be taken, in order to avoid local spread of the decease, in case of accidental rupture.

Postoperative anthelmintic chemotherapy (albendazole 400-800 mg/daily for 2 months), is advocated by the majority of surgeons [₁,₂].

In conclusion, spontaneous intrapleural rupture of a pulmonary echinococcal cyst constitutes a rare but severe event [₃,₇]. It usually causes pneumothorax, pleural effusion, empyema and secondary larval spread, as in this reported case [3]. High rate of suspicion is necessary when treating hydropneumothorax, especially in Echinococcus-endemic areas.

Correspondence to

George Lazopoulos MD, PhD, 24, Ellinikou Stratou str. 15237 Filothei Athens-Greece Tel.:+30 210 6854488 +30 6944 663208 E-mail: lazopoulosg@ath.forthnet.gr