Renal Echinococcosis: Clinical Study of 34 Cases

Vol. 157, 787-794, March 1997 Prtnted in U.S.A.

RENAL ECHINOCOCCOSIS: CLINICAL STUDY OF' 34 CASES JAVIER C. ANGULO, MANUEL SANCHEZ-CHAF'ADO, ALFONSO DIEGO, JOSE ESCRIBANO, JUAN C. TAMAYO AND LOPE MARTIN From the Departments of Urology and Radiology, Hospital Principe de Asturias, Alcala de Henares, and Department of Morphological

Sciences and Surgery, Uniuersidad de Alcala de Henares, Madrid, and Department Segouia, Spain

of

Urology, Hospital General de Segouia,

ABSTRACT

Purpose: Hydatid disease, a cyclo-zoonotic parasitic infestation caused by the larval stage of the cestode Echinococcus granulosus, is prevalent worldwide. We reviewed the clinical findings of a large series of renal hydatidosis treated in a n endemic area with special emphasis on diagnostic pitfalls. Materials and Methods: A retrospective 15-year review in a rural area of central Spain (600,000 population), with a global incidence of hydatidosis of 10 new cases per 100,000 population per year, revealed 34 with renal echinococcosis treated surgically (3 to 4% of officially confirmed cases of hydatidosis). Clinical, radiological and laboratory data were analyzed. Results: Renal hydatid disease mimicked other diseases. The combination of clinical history, imaging studies, a n d serological a n d urine investigation yielded a reliable pretreatment diagnosis in only 50% of cases and a presumptive diagnosis in 71%. Among imaging studies computerized tomography was the most valuable diagnostic examination. Moderate eosinophilia was found in half of the cases, while a third had scoleces in the urine. A diagnostic and therapeutic algorithm is presented. Conclusions: Preoperative diagnosis of renal hydatid disease is difficult even in a n endemic zone. Imaging studies are suggestive but usually inconclusive, and the differential diagnosis with a renal tumor or complicated cyst may not be made without surgery. Renal sparing surgery is possible in a significant proportion of cases, particularly when preoperative diagnosis has been considered. Significant surgical morbidity can be expected, and the risk of anaphylaxis and hydatid seeding, although low, should not be overlooked. KEY WORDS:echinococcosis, diagnosis, ludney neoplasms, cysts, parasites

Cystic hydatid disease is a cyclo-zoonotic parasitic infestation caused by the larval stage of the cestode Echinococcus granulosus.1 Human disease occurs endemically on all 5 continents and may also sporadically present in unexposed geographical regions due to increased travel and migration. The life cycle of E. granulosus requires 2 hosts and depends on the food chain. The adult worm is found in the small intestine of canids. Man is the intermediate host of a n aborted cycle. The eggs hatch in the intestine, and oncospheres penetrate the mucosa to the blood and lymphatic circulation for transport to the liver, lungs and other organs. These larvae grow slowly into hydatid cysts, thus producing space occupying lesions (fig. 1). Cysts usually grow the most within the first year and can survive latent for years or decades. Symptoms are often absent and in many cases echinococcal infection is a n incidental finding. Symptoms usually are due to a mass effect of the enlarging cyst in a confined space. Clinically discovered hydatidosis represents a minimal estimate of the number of cases affecting a population. Hydatid cysts may be present virtually in any organ but disease involving the urinary tract is relatively uncommon.* Most instances reported are single cases or comprise series with small numbers. Only a few studies have described a large number of patients.3-7 However, it should be remembered that renal or retrovesical cysts can be the urological manifestation of echinococcal disease and may cause a considerable diagnostic dilemma.8.9 We present the clinical findings of a large series of renal hydatidosis treated in an endemic area of central Spain with special emphasis on diagnostic and therapeutic pitfalls. Accepted for publication September 6, 1996.

MATERIALS AND METHODS

A retrospective 15-year review of the clinical records of 2 institutions covering a population of 600,000 from a rural area of Spain revealed 34 surgically treated and histopathologically confirmed cases of renal echinococcosis. Another 5 cases were clinically suspected but lack of histological confirmation precluded a conclusive differential diagnosis and, therefore, they are not included in this review. The global incidence of hydatid disease officially diagnosed in the same area, a shepherding region of central Spain, varies annually but is approximately 10/100,000 new cases annually. Therefore, clinically detected kidney involvement could represent approximately 3 to 4% of all cases of officially diagnosed hydatid disease in our environment. Although imaging modalities and laboratory investigation varied according to the year of diagnosis, most cases were homogeneously treated and all were histologically confirmed. Special attention was paid to the clinical picture, differential diagnosis, therapeutic approach and outcome. Patient age, symptoms and signs at presentation, size and focality of the lesion, data available from imaging modalities and serological findings, and the type of surgery and results were recorded for every case. RESULTS

No sex predominance was observed (male-to-female ratio 1.6:l). Patient age ranged from 3 to 80 years (mean age 49.5, 95%confidence interval 28.9 to 71.1) with a peak incidence in the 60s. Renal hydatid disease was rare in children younger than 15 years, with only 3 cases (9%)in this series. However,

787

RENAL ECHINOCOCCOSIS

788

Scolex attached to small intestine

\

Oncosphere

\

Oncosphere penetrates intestinal wall

Hydatid Cyst

MEN FIG. 1. Life cycle of E. granulosus

20% of t h e patients presented i n t h e first 3 decades of life. Retrospective investigation from medical records a n d patient contact revealed that more t h a n 60% lived permanently in a rural area. At least 70% of the patients confirmed that they had been in close contact with dogs, although only a small proportion (12%) were shepherds and used dogs to manage the flocks. The lesion was frequently solitary (85% of t h e cases), sometimes multifocal (15%)and rarely bilateral (6%). No side predominance w a s recorded. Maximum diameter of the lesion according to the surgical specimen, sonography or computerized tomography [CT) ranged from 4 to 18 cm. (mean 8.8, 95% confidence interval 5.4 to 12.2). Extrarenal hydatid disease was found in 44% of the cases and it was frequently discovered simultaneously with renal disease. History of hydatid cyst elsewhere was noted in only 18% of the cases. Extrarenal disease was noted in t h e liver in 29% of t h e cases, lung in 15%,retroperitoneum in 6% and spleen in 3%. Nonspecific symptoms t h a t led to discovery of the lesion varied. The most common were a palpable mass (41% of the cases), flank pain (35%1. gross hematuria (35%)and albuminuria 19%). A fourth of the cases were incidentally discovered on plain x-ray or a t exploration. Hydatiduria is a pathognomonic sign described as the passage of a typically grape-like material in the urine, usually accompanied by renal colic, and was noted in 18%of the cases secondary to rupture of the cyst into the collecting system of the kidney. Fever due to infection of the cyst occurred in 9'7 of the cases. Spontaneous renal rupture, a n extremely rare presentation, occurred in 1 case (3%1. The combination of different i m a g n g studies raised the preoperative suspicion of hydatid disease in 62% of t h e cases. However, if patients with the pathognomonic sign of hydati-

duria were excluded from analysis, imaging modalities were diagnostic i n 48% a n d merely confirmatory or helpful in preparation for surgery in 14'2. Only a simple x-ray was performed in every case. Excretory urography (IVP), pyelography and sometimes arteriography were also used i n the initial period. Sonography and CT had a role i n later years. Magnetic resonance imaging was performed only rarely. Plain abdominal radiography revealed calcification in 21 cases (62%), t h e morphology of which was linear in 70%, multi-laminated in 20% and amorphous in 10%' (fig. 2). M' was performed in 30 cases (88%), and it was a n excellent complement to plain x-ray, revealing some degree of distortion of the upper tract i n 86% with signs of compression in 80%, open caliceal ectasia in 20% and a nonfunctioning kidney i n 7% (fig. 3). A filling defect in t h e renal pelvis was present in 7% of t h e cases, suggesting transitional cell carcinoma. According to t h e medical records, renal malignancy was t h e initial diagnosis in 19 cases (56% of the total series) after IVP. Retrograde pyelography was performed in 9 cases (26%) in addition to a n IW. Antegrade and retrograde PYelography revealed displacement of the collecting system in 89% and communication with the urinary tract in 2 2 4 ofthe cases i n which both examinations were performed. Artenography in 5 cases (15%) revealed a n avascular pattern cornpressing the vascular tree, suggesting t h e benign nature of the process. Ultrasonography was performed i n 26 cases (76%), and was easily available and useful for defining t h e nature ofthe cyst and detecting asymptomatic cases. Mural calcifications and daughter cysts could also be seen on ultrasound. Most frequently t h e cystic lesion was multiloculated (11 cases, 42%) o r uniloculated (7,27%) but sometimes i t was heFr0geneous (5, 19%) or even solid (3, 12%, fig. 4). This atyP1Cd

RENAL ECHINOCOCCOSIS

789

also difficult to differentiate from a complicated renal cyst. Finally, a calcified unilocular mass was also impossible to distinguish from a complicated cyst or calcified renal cell carcinoma. Only 1 lesion (5%) appeared completely solid on CT due to secondary hemorrhage and infection. Although there is no typical CT appearance of renal hydatid disease, this was the most valuable examination to define the cystic nature and extent of disease, and also to evaluate the presence of complications, such as retroperitoneal seeding, cyst infection and renal atrophy. Combined IVP or retrograde pyelography with CT provided the best resolution to investigate a possible communication with the urinary tract. Magnetic resonance imaging, performed in 5 cases (15%), added nothing to CT. Moderate eosinophilia, retrospectively investigated, was present in 59% of the cases and parasite identification was possible in 32%. Opaque dots representing complete scoleces, brood capsules or hydatid sand with broken hooks were found in the h n e in 10-cases (fig. 6) and in the aspiration fluid from a percutaneous puncture in 1. These findings were unequivocal signs for diagnosis and, as with macroscopic hydatiduria, parasite identification in the urine implied communication of the cyst with the collecting system of the kidney. Scoleces and hydatid products in the urine were uniformly accompanied by significant pyuria. A skin test with hydatid fluid antigen (Casoni’s test) was performed in 14 patients and the reaction was positive in 6 (43%).Hemagglutination inhibition serology and latex agglutination performed in 19 patients were interpreted as positive in 15 (79%). These procedures were simple with high sensitivity. Counterimmunoelectrophoresis against “arc-5” was used recently in 7 cases with positive results. This test FIG.2. Linear curved calcification on plain x-ray appeared to be highly specific and, therefore, presented a good complement to indirect hemagglutination and latex agglutination, which can be used for screening. In summary, serological data generally supported the diagnosis of cystic hydatid disease in 16 cases (47%). Despite the integration of imaging studies, and microbiological and serological data, preoperative diagnosis remained doubtful in 50% of the cases. Furthermore, in 10 cases (29%) the diagnosis of renal hydatid disease had never been considered preoperatively. This diagnostic inaccuracy was greatest in the earlier years when CT and immunological studies were not performed. Diagnosis was achieved preoperatively in all cases with CT and counterimmunoelectrophoresis (7 during the last 3 years). Definitive therapy was cyst excision or pericystectomy in 7 cases (20%),partial nephrectomy in 6 (18%)and total radical nephrectomy in 21 (628). A lumbar approach was used for renal sparing surgery in 13 cases and for nephrectomy when preoperative diagnosis of renal hydatid disease had been FIG.3. Large mass severely compressing right kidney on considered in 9 to avoid peritoneal seeding. Combined renal and hepatic surgery was performed in 2 cases via a transtornogram. peritoneal approach, and pulmonary and renal disease was removed simultaneously in 1 via a thoracoabdominal apappearance on ultrasound, mimicking a solid lesion, was proach. Percutaneous puncture was not used as conservative mainly due to secondary changes from infection, hemorrhage therapy but was performed for diagnostic purposes in 4 cases (parasites were identified in 1 but no information was obor cyst rupture. CT in 22 cases (65%) usually revealed a unilocular or tained in 3). No complication presented after percutaneous multilocular cyst with a well-defined wall enhancing with aspiration. Irrigation with hypertonic serum or hydrogen contrast medium and occasional calcifications (fig. 5). Multi- peroxide was performed in 62% of the cases for preoperative vesicular cysts with mixed density due to viable daughter or intraoperative suspicion of hydatid disease. Controlled cysts were useful diagnostic signs in 8 cases (38%)in which opening of the cyst in the operative field was performed in 4 CT was done. Noticeably, the density of daughter cysts was cases to aid surgery, while involuntary rupture occurred in 2. always less than that of the mother hydatid cyst. Sometimes Therefore, the cyst was opened intraoperatively in 6 patients the peripheral wall of a multiloculated mass did not enhance (18%)and prophylactic irrigation was performed. Nephrectomy was delayed due to hemorrhage and urinary with contrast medium and the differential diagnosis of a multilocular cyst or cystic renal cell carcinoma was not pos- fistula in 2 cases in which the kidney had been initially sible, particularly when the cyst was small. One case in a preserved. Therefore, nephron sparing surgery was successchild was interpreted as a cystic nephroma. Univesicular ful in 32% of our cases. The serious complications of hydatid disease without daughter cysts and without calcification was disease, that is anaphylaxis and seeding, were rare. Node-

790

RENAL ECHINOCOCCOSIS

FIG. 4. Sonography reveals mixed lesion with peripherally located daughter cysts and echogenic central area (A), and nonspecific heterogeneous lesion ( B ) .

FIG.5. CT reveals pathognomonic lesion with well-defined wall and peripheral daughter cysts (A),and unilocular high density cystic mass with complete peripheral calcification (B).

Mediterranean, Afi-ica, Latin America and Australia.' Migration and increased travel make its presentation potential worldwide. Humans are infected by close contact with dogs carrying embryonic eggs, or gravid segments containing hundreds of eggs in hair, saliva or anal region. Eggs are resistant and can live several months outdoors in cool, damp areas. Therefore, parasite ingestion through infected fruits or vegetables is common. Sheep are the usual intermediate hosts, although another herbivore, such as man, can be the intermediate host of an aborted cycle. Oncospheres hatch and penetrate the intestinal wall, disseminating primarily to the liver, secondarily to the lung and finally anywhere in the body to form unilocular cysts. The unilocular vesicle is limited by a nucleated cellular sheet named the internal germinal membrane, which is surrounded by the external laminated membrane. Evolution of these structures gives rise to a hydatid cyst. The germinal membrane produces the fertile elements, the scoleces, that swim in a hyaline clear fluid and accumulate, making up the hydatid sand. Unilocular cysts grow and become multivesicular structures by formation of daughter vesicles, secondary to fragmentation and folding of the germinal membrane. The acellular multilayered laminated membrane allows nutrition by osmosis and prevents dissemination. The reaction in the host produces the most external covering, the pericyst, a fibrous wall that contacts the parenchyma of the organ that DISCUSSION harbors the cyst. Despite preventive efforts, echinococcal disease continues Dogs and other carnivores become infected by feeding on to be endemic in sheep and cattle raising countries of the viscera with hydatid cysts. Liberated scoleces attach to the

thal systemic anaphylaxis occurred in 1 case (3%)and retro) . 1of the peritoneal hydatid seeding was detected in 2 ( 6 7 ~In latter 2 cases extrarenal retroperitoneal seeding was detected preoperatively and albendazole chemotherapy was administered. Except for the aforementioned delayed nephrectomies, surgical complications included retroperitoneal hematoma in 1case, urinary fistula treated conservatively in 1 and postoperative minor infection in 3. There was no treatment related mortality. Followup was variable but no patient died of hydatid disease. Similarly, no lesion recurred in the kidney and no patient had contralateral asynchronous renal disease. On the other hand, extrarenal disease after treatment of renal hydatid cysts was clinically detected in 5 cases. Routine serological investigations, for example the complement fixation test, were not performed to document healing postoperatively. Five patients were suspected to have renal hydatid disease but they did not undergo surgery and, therefore, they were excluded from this review. One patient refused surgery despite active hepatic and renal disease, and he was lost to followup. One patient had coexisting advanced malignancy, and 3 were elderly patients with presumptive inactive disease followed for 1.5 to 4 years without evidence of progression.

RENAL ECHINOCOCCOSIS

791

are frequent but are also nonspecific. We detected calcifications in 62% of cases of renal hydatidosis, mainly curvilinear, sometimes multilaminated and rarely amorphous. A review of 10 years of experience with calcified renal masses at the Mayo Clinic showed that 5% were benign cysts with peripheral eggshell calcifications and only 0.9% was calcified hydatid cysts." Noticeably, 87% of the renal masses containing calcium in that series were malignant. Detection of daughter vesicles on ultrasound or CT is also characteristic of a hydatid cyst. Ultrasonography is the initial diagnostic tool, since it is available worldwide, is inexpensive and can diagnose typical unilocular or multilocular cysts in the majority of ca~es.~.12 However CT appears to provide more information, and may be necessary for complicated cysts and in the differential diagnosis of renal cell carcinoma. CT may diagnose hydatid disease but it also provides a good description of residual parenchyma, shows a possible communication with the urinary tract and demonstrates the presence of extrarenal disease. Daughter cysts within a large cyst and increased density of the hydatid membrane, which enhances aRer injection of intravenous contrast material, is a pathognomonic sign found in 38% of our cases in which CT was performed. As proposed by oththat the CT density of viable daughter cysts e r ~ l4 , ~we~ noted . was always less than that of mother cysts. However, diagnosis is not always easy. We found cases in which a univesicular hydatid cyst and a thickened calcified infected cyst were impossible to distinguish. In other instances unilocular disease was interpreted as a necrotic, sometimes calcified, renal cell carcinoma. The multilocular FIG. 6. Free scoleces in urine form of a hydatid cyst was mistaken for a multilocular cyst, cystic nephroma and the cystic variant of a renal cell carcinoma. An infected cyst was interpreted as a renal abscess, small intestine, where they develop into adult tapeworms. and secondary hemorrhage and infection also appeared as a However, for several reasons a hydatid cyst may lack infec- solid mass. Percutaneous aspiration of cyst fluid can be helptive potential. Sometimes unilocular cysts formed after dis- ful for preoperative diagnosis but it has been routinely dissemination of oncospheres lack scoleces and, therefore, they couraged due to the risk of serious allergic reactions or focal are called sterile cysts or acephalocysts. In other instances dissemination. Fine needle aspiration may not be as risky as separation of the germinal layer and laminated membrane previously considered, and this procedure can be risk-free if caused by growth of the cyst or minor trauma gives rise to a performed with systemic albendazole therapy.15 The Casoni intradermal skin test was formerly used to nutritional defect and loss of the germinal membrane. Finally, complete peripheral calcification of the cyst may also suggest the diagnosis but many serological (immunological) compromise nutrition and cause death of larvae. Secondary methods have replaced it to diagnose human hydatidosis, infection with bacteria in this form of inactive disease may including latex agglutination, indirect hemagglutination, counterimmunoelectrophoresis, enzyme-linked immunosorlead to presentation as a renal abscess. The clinical picture of hydatid cyst of the urinary tract is bent assay with whole hydatid fluid and with antigen 5, and seldom sufficiently characteristic to suggest the diagnosis a thermolabile lipoprotein that elicits the arc-5 precipitin line preoperatively. Our experience reveals that even in a n en- in immunoelectrophoresis. Indirect hemagglutination and demic area, despite the integration of several imaging stud- enzyme-linked immunosorbent assay are the most sensitive ies, microbiological investigation, serological information and tests but they may provide false-negative data due to circua high index of suspicion, the diagnosis of renal hydatid lating immune complexes or false-positive data secondary to disease is not considered preoperatively in 1 of 3 patients. cross-reactivity with other parasitic infections, such as cysEven when considered significant doubt remains in a high ticercus and schistosomiasis.16 However, the diagnosis can be proportion of cases and pretreatment diagnosis is made in narrowed by immunoelectrophoresis or counterimmunoeleconly 1 of 2. Clinical presentation is heterogeneous, since the trophoresis to detect specific antibodies against antigens isodisease can occur as a renal mass, or with positive serology or lated from hydatid cyst fluid." In this sense, double diffusion several varied symptoms. We propose a n algorithm to arc-5 is considered the most specific test. However, it has achieve diagnosis that considers clinical findings, imaging been recently described that the specificity of enzyme-linked modalities, laboratory data and cytological information immunosorbent assay can be greatly increased using ovine serum and phosphorylcholine in the diluent buffer, thus (fig. 7 ) . Except for hydatiduria or passage of grape-like material in showing 80%sensitivity and 100% specificity.ls Our diagnosthe urine, usually accompanied by renal colic, presenting tic algorithm is primarily based on indirect hemagglutination symptoms are nonspecific. Eosinophilia and close contact or enzyme-linked immunosorbent assay, and arc-5 is used for with dogs or husbandry practices should always be investi- confirmation (fig. 7). It is controversial whether serological tests should be used gated when a complex cystic lesion of the kidney is found. The search for scoleces, broken hooks or brood capsules in urine for screening in endemic areas. We share the opinion that serology is generally more specific but less sensitive than should also be encouraged.1° Findings at imaging studies are frequently suggestive of imaging.17 Therefore, in developed endemic areas screening hydatid disease but usually inconclusive, and differentiation should be based more on diagnostic imaging, that is ultrafrom renal tumor or a complicated cyst may not be made sonography, rather than serology. Indirect hemagglutination without surgery. Ring-shaped calcifications in the renal area has been used satisfactorily in our environment aa a screen-

792

RENAL ECHINOCOCCOSIS

,

Palpable mass

Flank pain

Hematuria

1

Calcification on X-ray

ULTRASOUND

I

+

Renal mass of mixed echogenicity

t

Hydatiduria

Eosinophils

Yes

Raised

Normal

IHA/ELlSA

++ I

Positive

+ -

L

Negative

L, CT-SCAN 1

ARC-5

HYDATID CYST

J.

IVU RETROGRADE

4

+

t

Doubt

II

1

--t

Radical Surgery

Percutaneous Aspiration

;

Non-communicating

Communicating

Nephron-sparing surgery if possible

Doubt

Escolex in urine

FIG.7. Diagnostic algorithm for renal hydatidosis. IHA. indirect hemagglutinin. ELISA, enzyme-linked immunosorbent assay. NU, IVP

ing parameter for patients carrying t h e disease at an early phase within a high risk asymptomatic population composed of households living with patients with hydatid disease.19 In this sense the hydatid antigen dot immunobinding assay is a simple, new diagnostic test with good predictive value for human hydatid disease, particularly suitable for large scale field screening. The presence of parasite specific antibodies leads to dyeing of the stick-reactive area a n d a colored spot appears.20 Another potential use of serology is to control the effectiveness of therapy. The complement fixation test becomes negative several months after removal or death of the cyst. Cyst removal without contaminating the patient is the goal of therapy. There is a cleavage plane between t h e pericyst and laminated external membrane through which blunt dissection can be performed. However, this maneuver is dangerous because the high internal pressure of t h e cyst may cause rupture and fluid spillage. This accident would imply parasite liberation, and scoleces or microscopic fragments of the germinal epithelium could become entirely new cysts, lead-

ing to hydatid peritoneal or retroperitoneal dissemination. Rupture of a cyst also causes allergic manifestations that vary from pruritus and urticaria to anaphylactic shock and even death. To prevent these serious complications great care m u s t be taken during surgery to remove t h e cyst intact. Controlled evacuation is a good alternative when the hydatid fluid is under high tension. In addition, before resection the area of the cyst is swabbed with a scolecidal solution, such as hypertonic saline solution or hydrogen peroxide, and albendazole chemotherapy h a s been advocated i n case of leakage of t h e hydatid fluid ( 10 to 15 mg./kg. daily for 8 weeks). We did not use routine antihelminthic agents in the absence of surgical spillage because of drug hepatic toxicity.2' Following these preventive measures anaphylaxis and seeding are rare, a n d occurred in 3 and 6 8 of t h e cases, respectively. Complications related to renal sparing surgery can be expected, particularly hemorrhage which may be caused by profuse bleeding of a vascularized aduentitia. The optimum therapy and time to treat cystic hydatid disease should be individualized for every patient. Less than

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RENAL ECHINOCOCCOSIS

10% of the cases are fatal but considerable morbidity can be expected if the disease is untreated.1.22 Surgical resection remains the treatment of choice for uncomplicated cases but cysts in the brain or bone and multiple cysts can be treated with albendazole, particularly when they are actively growing.’,’ Percutaneous drainage and alcohol instillation have been recently presented as safe and minimally invasive therapeutic options for renal hydatidosis.17.24.25 However, reported experience is limited, followup is short and failure of the kidney preservation strategy has been described.25 We understand that there is not yet enough evidence to propose this approach as the first therapeutic option. Further work is needed to determine the safety and efficacy of this new form of therapy. We believe that a renal sparing approach should be intended when preoperative diagnosis of hydatidosis has been considered. Renal conservative surgery is possible even for large lesions.”” Cystectomy is the simplest technique and can be followed safely by pedicled omentoplasty to treat a residual cavity.27We have used this technique for young, clear cysts with a thin, noncalcified pericyst. If there is a thickened or calcified peiicyst total or subtotal pericystectomy may be necessary. Small peripheral lesions are also candidates for partial nephrectomy, particularly when diagnostic doubt persists or communication with the urinary tract is suspected to prevent a residual fistula. A nephrostomy tube may be necessary in such cases. Ex vivo renal surgery and autotransplantation have also been reported.28 Communicating renal hydatid disease can also be treated with cystectomy and careful closure of the communication. Total or radical nephrectomy is frequent when the preoperative diagnosis is not conclusive. Total nephrectomy is also electively performed for large lesions when the cyst causes tissue damage by pressure atrophy, and in cases with evident communication with the urinary tract (open hydatiduria, parasite identification in urine or filling defect on IVP). It remains unresolved whether the risk of implantation within the urinary tract and bladder justifies nephroureterectomy.16 Other complications, such as renal rupture, cyst hemorrhage and cyst infection, are also indications for total neDhrectomv. When disease is exclusively renal the patient can be treated more safely via a lumbar approach, since the risk of dissemination into the peritoneal cavity is avoided. An incision above the 11th or 12th rib can be used to reach the upper pole. However, the optimal approach depends on the certainty of preoperative diagnosis and the extent of disease (fig. 8).Bilateral and multiple organ disease requires a transperitoneal or thoracoabdominal approach. The treatment of polyvisceral hydatidosis depends on the general state of the patient and requires multidisciplinary surgery, sometimes with

a several stage operation.”” An unidentified renal mass usually requires radical nephrectomy through a transperitoneal approach as well. Whenever a lesion is not identified preoperatively but a decision is made to perform a renal sparing procedure, a lumbar approach is elected. Asymptomatic elderly patients may be left untreated, particularly when inactive disease is suspected based on changes in cyst volume and density, small size of the lesion that does not increase during followup, complete peripheral calcification and a decrease in the titer of specific immunoglobulin E. However, patient monitoring is advised since there are no firm criteria for parasite inactivation. To our knowledge the evolution of untreated renal hydatid disease is unknown. However, a comparison with the natural history of hydatid disease of the lung and liver and our own experience reveal that actively growing cysts are undoubtedly indications for surgery. Pressure exerted by the growing cyst invariably damages the kidney. We also observed renal rupture, cyst infection, retroperitoneal hemorrhage and perirenal hydatid seeding. On the other hand, surgery related complications should not be overlooked. The risk of surgical spillage and severe allergic reaction to the cyst should be considered. Also, a renal preserving strategy may fail. However, medical management of disease is far from being a realistic option to surgery and should be conceived as adjuvant therapy or a n alternative for poor surgical candidates. Renal hydatid disease should be considered in the differential diagnosis of space occupying lesions of the urinary tract a t any age, particularly in an endemic area. Accurate preoperative diagnosis sometimes makes possible a renal preserving strategy. Prevention and control of hydatid disease could be achieved if several health education measures were observed in a n endemic zone. Mass chemotherapy of dogs with praziquantel would eliminate the adult worms.’ Behavioral habits resulting in domestic dog-to-human contact should be corrected, particularly since the majority of our cases of hydatid disease seemed to be transmitted through a domestic cycle. Finally, alimentary habits of domestic dogs should be strictly supervised, since they become infected after feeding with viscera containing hydatid cysts due to inadequate disposal of infected organs. CONCLUSIONS

A high index of suspicion is needed for preoperative diagnoses of renal hydatid disease, since this is difficult even in endemic areas. The combination of clinical history, imaging studies, serological and urine investigations yields reliable pretreatment diagnosis in only 50% and presumptive diagnosis in 71% of the cases. The imaging spectrum of disease

Lumbar approach

Preoperative1y identified as hydatid

--L---l

Unidentified renal mass to be treated consenratively

Transperitoneal approach

Thoraco-abdominal approach

I

I

Unidentifiedrenal mass to be treated radically

Hydatid of multiple organs

I

Non-communicating

communicating

Cystectomy Par!ial and closure of Nephrectorny communication

I Total Cystectomy Partial Nephrectomy Nephrectomy

I Radical Nephrectomy

F I ~ ;8. . Algorithm of surgical strategies for renal hydatidosis

I Multidisciplinary surgery

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RENAL ECHINOCOCCOSIS

varies. CT is the most useful diagnostic modality. Therapeutic decisions should be individualized, and preoperative evaluation of disease extent and signs of activity is mandatory. A renal sparing approach is desirable when preoperative diagnosis i s considered. Small lesions without communication to the urinary tract a r e preferred for this conservative approach. Serious complications of surgery of hydatid disease (severe allergic reaction and parasite dissemination) a r e rare with use of irrigation with hypertonic serum or hydrogen peroxide. REFERENCES

1. McGreevy, P. C. and Nelson, G. S.: Larval cestode infections. In: Hunter's Tropical Medicine, 7th ed. Edited by G. T. Strickland. Philadelphia: W. B. Saunders Co., pp. 843-859, 1991. 2. Kirkland, K.: Urological aspects of hydatid disease. Brit. J. Urol., 3 8 241, 1966. 3. Al-Ani, M. A. J. and Al-Waili, N. S.: Renal hydatid cysts: report of 15 cases. Saudi Med. J.. 7: 478, 1986. 4. Benjelloun, S. and Elmrini, M.: Le kyste hydatique du rein ( a propos de 45 CaSJ. Prog. Urol., 3: 209, 1993. 5. Beddouch, A., Ait-Houssa, M., Alkandry,.S., Lazrek, M. and Draoui, D.: Le kyste hydatique renal. A propos de 22 cas. J. dUrol., 100: 304. 1994. 6 Mzali, R.. Bahloul. A,, Wali, M., Baati, S,, Mhiri, N. and Beyrouti, M. I.: Le kyste hydatique du rein. Apropos de 18 cas. Ann. Urol., 2 9 143, 1995. 7 Odev, K., Kdinc. M., Arslan, A., Aygiin, E., Giingor, S., Durak, A. C. and Yilmaz. K.: Renal hydatid cysts and the evaluation of their radiologic images. Eur. Urol., 3 0 40, 1996. 8 Von Sinner, W. N., Hellstrom, M., Kagevi, I. and Norlen, B. J.: Hvdatid disease of the urinarv tract. J. Urol.. 1 4 9 577. 1993. 9. Af&, H., Yagci, F.. Meto, $. and Aybasti, N.: Hydatid disease of the kidney: evaluation and features of diagnostic procedures. J. Urol., 151: 567, 1994. 10. Noi. I.. Cohen. I. and Loberant, N.: Renal hydatid cyst: urinary cytological diagnosis. Diagn. Cytopathol.. 12: 152, 1995. 11. Daniel, W. W., Jr., Hartman, G. W., Witten, D. M., Farrow, G. M. and Kelalis, P. P.: Calcified renal masses. A review of ten years experience at the Mayo Clinic. Radiology, 103: 503, 1972. 12. Beggs. I.: The radiological appearances of hydatid disease of the liver. Clin. Rad., 34: 555, 1983. 13. Kalovidouris, A., Pissiotis, C., Pontifex. G., Gouliamos, A,, Pentea, S. and Papavassiliou, C.: CT characterization of multivesicular hydatid cysts. J. Comput. Assist. Tomogr., 1 0 428, 1986. 14. Karabekios, S., Gouliamos, A., Kalovidouris, A., Vlahos, L., Papavassiliou. C. and Sakkas. J.: Features of computed tomography in hydatid cysts of the urinary tract. Brit. J. Urol., 64: 575, 1989.

15. Goel, M. C., Sharma, B. C. and Baijal, S. S.: Re: hydatid disease of the kidney: evaluation and features of diagnostic procedures. Letter to the Editor. J. Urol., 152: 2104, 1994. 16. Shetty, S . D., Al-Saigh. A., Ibrahim, A. I., Patil, K. P. and Bhattachan, C. L.: Management of hydatid cysts of the urinary tract. Brit. J. Urol., 7 0 258, 1992. 17. Babba, H., Messedi, A., Masmoudi, S., Zribi, M., Grillot, R., Ambriose-Thomas, P., Beyrouti, I. and Sahnoun, Y.: Diagnosis of human hydatidosis: comparison between imaginery and six serologic techniques. Amer. J. Trop. Med. Hyg., 5 0 64, 1994. 18. Planchart, S., Botto, C., Alarcon de Noya, B., Bonifacino, R.. Vivas, L., Spencer, L. and Vivas, S.: Evaluation of the double diffusion, enzyme immunoassay and immunoblotting techniques, for the diagnosis of human hydatid disease in tropical areas. Rev. Inst. Med. Trop. SBo Paulo, 36: 205, 1994. 19. Perez-Rodriguez, E., Bollo, E., Navio, P., Zapatero, J.,Flores, J., Ortiz de Saracho, J. and Gaudo, J.: Estudio epidemiologico en familiares de pacientes con enfermedad hidatidica. iPoblacion de alto riesgo? Rev. Clin. Esp., 195 138, 1995. 20. Mistrello, G., Gentili, M., Falagiani, P., Roncarolo, D., Riva, G. and Tinelli, M.: Dot immunobinding assay as a new diagnostic test for human hydatid disease. Immunol. Lett., 47: 79, 1995. 21. Morris, D. L. and Smith, P. G.: Albendazole in hydatid diseasehepatocellular toxicity. Trans. Roy. SOC.Trop. Med. Hyg., 81: 343, 1987. 22. Christopher, P. J. and Lupez, W. A.: Hydatid disease notifications in New South Wales. Med. J. Aust., 1: 54, 1970. 23. Todorov, T., Vutova, K., Petkov, D., Mechkov, G. and Kolev, K.: Albendazole treatment of human cystic echinococcosis. Trans. Roy. SOC. Trop. Med. Hyg., 82: 453, 1988. 24. Baijal, S . S., Basarge, N., Srinadh, E. S., Mittal, B. R. and Kumar, A,: Percutaneous management of renal hydatidosis: a minimally invasive therapeutic option. J. Urol., 1 5 3 1199, 1995. 25. Goel, M. C., Agarwal, M. R. and Misra, A.: Percutaneous drainage of renal hydatid cyst: early results and follow-up. Brit. J. Urol., 7 5 724, 1995. 26. Roy-Choudhury, S. and Maji, B. P.: Renal salvage from a giant multiloculated primary echinococcal cyst. Int. Urol. Nephrol., 27: 141, 1995. 27. Beyribey, S., Cetinkaya, M., Adsan, 0..CoSkun, F. and Ozturk, B.: Treatment of renal hydatid disease by pedicled omentoplasty. J. Urol., 154: 25, 1995. 28. Tscholl, R. and Ausfeld, R.: Renal replantation (orthotopic autotransplantation) for echinococcosis of the kidney. J. Urol., 133: 456, 1985. 29. Mentouri, B.: Treatment of hydatid disease of the liver. In: Surgery of the Liver, Biliary Tree and Pancreas. Edited by A. Cirenei and W. Hess. Padova: Piccin Editore, pp. 55-62, 1979.