Omental and Retroperitoneal Hydatid Cyst: A Case Report

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Omental and Retroperitoneal Hydatid Cysta b cFig 1. a-c. Solid mass in right seminal vesicle with calcification. A large prostate is obvious.aFig 2. a,b. A 4 cm hypodense lesion in right lobe of liver.bCT scan of the abdomen with contrast revealed a hypodenselesion of about 4 cm located in the subdiaphragmaticregion in the right liver lobe, with partialenhancement (Figure 2); a thick-walled cysticlesion of about 5*5 cm that bore a mural nodule, andwas located among the duodenum, aorta and left kidney(Figure 3); and still a third lesion of about 5*5 cmon the left, among the normal bowel loops, suspectedto be a prostatic mass with extension to the seminalvesicles.The differential diagnoses based on these findingson CT scan were pancreatic pseudocyst, dermoid cyst,duplication cyst and necrotic lymph node.Testis sonography was recommended. The sonographyof testis reported a solid mass with flakes of calcificationin the right seminal vesicle. The prostate andbladder were reported to be normal.The patient underwent a laparotomy, where thethree cysts were macroscopically recognized to resemblehydatid cysts. One cyst was found to be locatedin the right lobe of the liver adajacent to thegall bladder, which was managed by evacuation andomentoplasty. Another cyst, 5×5 cm, was found behindthe bladder over the omentum, which was resected,and the third cyst, 5×5 cm, was detected nearthe ligament of Treitz, which was also successfullyresected. The Cysts were approved microscopically(Figure 4).DiscussionHydatid disease is a result of infection by Echinococcusgranulosus. Humans may become accidentalhosts after close contact with infected dogs. 1 Our casehad a higher probability of having hydatid disease forbeing a farmer in close contact with the domestics,less sanitary conditions and poorer self-care, and havinglower access to medical care.Hydatid cysts may be found in almost any site of thebody, either from primary inoculation or via secondaryspread. The liver is affected in approximatelytwo-third of patients, as in our case as well. 2Primary peritoneal hydatid cyst is extremely rareand is usually secondary to hepatic disease. The overallfrequency of peritoneal echinococcosis is approximately13%. Most of these cases are related toprevious surgery for hepatic disease. Still, spontaneousasymptomatic microruptures of hepatic cysts intoperitoneal cavity are notuncommon.8In thepresent case, a historyof falling down couldhave caused the ruptureof the hepatic hydatidcyst leading to the involvementof peritonealcavity. Also, due to thepresence of multiplecysts (3 cysts), it couldbe concluded that it218 Iran. J. Radiol., Summer 2006, 3(4)
Sirus et al.a b cFig 3. a-c. Cystic lesion, thick-walled with mural nodule.abcould have been secondary to shedding from onecyst, probably following a trauma, as the patients reportedan incident of falling from the horse back longago, the released daughter cysts could have formedthe other 2 cysts. Still, this hypothesis cannot be supportedby plausible evidence.E. granulosus infection of the liver frequently producesno symptoms. The right lobe is affected in 60 to85 percent of patients, as was in our case. Significantsymptoms are unusual before the cyst has reached atleast 10cm in diameter. 9 Peritoneal echinococcosisusually goes undetected until cysts are large enoughto produce symptoms. 8,10,11 In our case the patient hadright upper quadrant pain with a cyst that measured5×5 cm on CT scan.Isolated retroperitoneal hydatid cyst is rare and it isusually the result of spontaneous, traumatic or surgicalrupture of a primary hepatic cyst. 12,13In the present case, one of the cysts was retroperitoneal,among the left kidney, duodenum and abdominalaorta and the patient had a history of previoustrauma.The calcification and enlargement of the rightseminal vesicle with normal pathologic result in ourpatients could be due to a dead hydatid cyst. Althoughisolated hydatid cyst in a seminal vesicle hasnot been reported previously, in the present case thepossibility for the secondary involvement of seminalvesicles from abdominal hydatid cysts exists and thenormal biopsy can be the result of sampling from theadjacent normal tissue. 13 Since no further investigationof the lesion was done after the normal biopsyreport, its true etiology cannot be cleared.Routine laboratory tests, including complete bloodcounts and liver function tests, may be abnormal butare nonspecific and cannot make a diagnosis. In ourpatient the laboratory findings were all normal.CT scan is the imaging of choice for determiningthe number, size and anatomic location of cysts, andis also superior to ultrasound in detecting extrahepaticcysts. 7 Imaging findings in hydatid diseasedepend on the stage of the cyst growth. It means,whether the cyst is unilocular, contains daughtervesicles, contains daughter cysts, is partially calcified,or is completely calcified (dead), the imaging defers.So the range of differential diagnosis is wide andmissed cases are common. In the present case, theunusual location of the cysts and the shape of the cystwith thick wall and mural nodule on CT, suggesteddifferential diagnoses of pancreatic pseudocyst or necroticlymph nodes probable.Therefore, it is to emphasize that in any cystic lesionin any anatomic location, hydatid cyst should beconsidered at least as a differential diagnosis especiallyin places that hydatid cyst is endemic.Fig 4. The Phatologic feature of the cystsIran. J. Radiol., Summer 2006, 3(4) 219
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Omental and Retroperitoneal Hydatid Cyst: A Case Report

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