echinococcus multilocularis is the fox tapeworm and the most pathogenic one among the 4 zoonotic species of the genus echinococcus , and thus e. multilocularis can cause an infection resulting in a potentially fatal chronic liver infection called human alveolar echinococcosis ( ae ) . e. multilocularis has an extensive geographic range , mainly across the northern hemisphere , including endemic regions in central europe , most of northern and central eurasia , extending eastward to japan and parts of north america . the intermediate hosts , mostly rodents and ungulates including humans , are infected by accidental ingestion of eggs shed in the feces of the definitive hosts . the metacestodes go through the small intestine and mostly reach the liver , but also other organs such as the lung and brain . human ae is a potentially fatal , chronically progressive hepatic infection with e. multilocularis , that is characterized by a long asymptomatic incubation period during which an invasive tumor - like multi - vesicular and exogenously budding mass - like lesion is developed . the parasitic lesion composes of dense granulomatous infiltration and microcalcifications microscopically , and eventually necrotic cavitation may occur . in korea , ae has never been reported , and herein , we report the first written case of human hepatic ae in a southeastern korean district , gimhae - si ( city ) . a 41-year - old woman residing in gimhae - si , gyeongsangnam - do , korea transferred to dong - a university hospital on 5 april 2002 for evaluation of the known hepatic mass . she denied any contact history with domestic animals or pets as well as livestock , and has not visited zoo and never traveled abroad . on 17 september 2001 routine radiologic examinations revealed a hepatic mass , and the pathologic findings of needle biopsied mass were described as coagulation necrosis . at dong - a university hospital , the liver showed an 8 cm sized ill - defined mass with 1.5 cm and 3 cm sized satellite nodules at the left lateral segment of the liver without lymph node enlargement on ct imaging . although non - neoplastic mass was considered , malignancy such as cholangiocarcinoma should be ruled out radiologically . laboratory data from routine cbc , chemistry , serology , electrolyte profiles , hormone analysis of blood , tumor markers ( -fetoprotein , carcinoembryonic antigen , and ca 19 - 9 ) , and urine analysis were all within normal limits . to rule out any possibility of malignancy , left hepatectomy was done . during operation , the lobectomized liver showed a relatively demarcated mass , 11 cm in greatest dimension and abutted several nodular masses of 1 - 3 cm in diameter , which showed necrosis on cut surface , grossly . histologically , extensive coagulation necrosis , granulomas , and dispersed acellular membranous shells within cystic spaces were observed . these gross and histologic findings corresponded with a parasitic infection of the liver , but identification of the specific parasite species was not processed . she was discharged without complications . during follow - up , on 19 july 2005 , a new nodular mass , 4.53.0 cm was observed in s5/8 segment of post - hepatectomized liver on ct imaging , and a needle biopsy of the mass showed coagulation necrosis . the hepatic mass was checked to be enlarged to 6.34.5 cm and several small nodules in both basal lungs on 7 august 2007 . the hepatic mass showed extensive necrosis , and the pulmonary nodules represented calcification and focally impinged air , suggesting calcified granuloma rather than metastatic malignancy . on 7 may 2010 , the hepatic mass was more enlarged , up to 10 cm in diameter and right supradiaphragmatic lymph node enlargement was found on contrast enhanced ct scan . relatively well defined small nodules were seen in both lower lobes of the lung , suggestive for calcified granulomas , and metastasis , even less likely ( fig . the eosinophilic count was 8.9% ( reference value : 0 - 7% ) , total ige was 1,944 ku / l ( reference value : 0 - 200 ku / l ) , and parasitological studies were all negative for helminths , including ascaris lumbricoides , trichuris trichiura , enterobius vermicularis , hookworms , and protozoa . a second operation , including a partial anterior resection , was done but the hepatic mass was not completely removed . the resected liver mass , measuring 16.29.54.3 cm was rimmed by raggedy , thickened , fibrotic or myxoid glisson 's capsule , focally adhered with fat tissues , and underlying parenchyme showed total necrosis in greenish yellow color , and normal liver was not present . the cut surfaces on serial sections were spongy , with mostly small and occasionally large cystic spaces ( fig . the cystic spaces were empty or filled with mucoid exudates , and inner surface was rimmed by more yellow wall . between the cysts , microscopically , the mass showed diffuse and extensive necrosis with totally effaced liver tissues . among necrosis , numerous variable - sized multilocular cysts with discernible lining were observed . the cysts contained ribbon - like eosinophilic laminated layers , characteristic for e. multilocularis , which appeared more strongly red by periodic acid - schiff ( pas ) stain ( fig . chronic granulomatous inflammation , composing of proliferating epithelioid cells surrounding the organisms , and infiltration of lymphoplasma cells , a few eosinophils , and giant cells were observed at the periphery of the mass ( fig . we could approach this unusual hepatic mass , mimicking clinical features of malignancy after consultation to professor jong - yil chai , department of parasitology and tropical medicine , seoul national university college of medicine , seoul , korea . we concluded that these findings corresponded well with hepatic alveolar echinococcosis although korea is not an endemic area for this cestode disease . she was discharged after the second operation without comlpication . during about 14 months of follow - up period , she has taken 800 mg of albendazole , orally in 2 divided doses , without any symptom . follow - up radiologic tests showed unremarkable changes of the remaining mass on the remnant liver , and slightly decreased size of pulmonary nodules . although , hokkaido of japan 's northmost island is known as an endemic area   and in these days , the endemic areas have expanded , in korea , human ae is not notified to our knowledge . furthermore , in non - endemic areas , ae is enough to be confused with malignant tumor and misdiagnosed . we experienced an unusual clinical case , complaining of a hepatic mass with histological features of non - neoplastic and suggestive of a parasite infection and continuous clinical suspicion of malignant tumor for 10 years . even she has been residing in gimhae city which is a recently developed and industrialized area , but was a rural community , she denied any history of contact with domestic animals or pets as well as livestock and has been never visited other countries . in this regard , it is strongly suggested that a possible infection route from imported animals may be underlaid . concerning a literature review of human cestode infections in korea , min   recognized that most human hydatidosis cases have been imported ones , from outside of korea , except 1 possible indigenous case , and they were all caused by cystic hydatidosis ( ce ) due to echinococcus granulosus , not ae . it has a risk of metastasis in advanced stages , usually resulting in secondary lesions in the lung or brain . a fatal outcome may occur in over 95% of untreated patients within a 10-year period following diagnosis . when a slowly growing tumor , visualized by imaging techniques , is detected , a case is verified if at least 2 of the following 4 parameters are fulfilled , according to the who recommendations : 1 ) typical organ lesions detected by imaging techniques , e.g. , abdominal ultrasound , ct , and magnetic resonance imaging , 2 ) detection of e. multilocularis specific serum antibodies by serotests , 3 ) histopathology compatible with ae , 4 ) detection of e. multilocularis nucleic acid in a clinical specimen . ct imaging of slow growing and recurred mass in this case displayed ill - defined hypodense mass with poor or no enhancement after contrast injection and no differences on arterial and portal phase , which is characteristic for hepatic ae . during the follow - up period of our case however , it is sometimes difficult to rule out other parasitic infections , pathologically and clinically , especially in non - endemic areas . multiple cysts , mostly empty and histologically lamellated membrane along the inner side of the cysts with characteristic pas ( + ) stain , are compatible with ae . lymphatic spread has been hypothesized to constitute a route for dissemination , however , the actual human involvement of lymph nodes in ae has not been frequently reported . in our case , we had not performed serologic and molecular studies for detection of e. multicularis - specific serum antibodies and nucleic acids until just prior to publication of this paper . however , these studies were subsequently performed and the results will be published elsewhere . in endemic areas , ae is considered the most serious parasitic zoonosis and ae incidence may increase in the future though the incidence is different among regions . thus , molecular and immunological technology for detection of humans and animals infected with e. multicularis as well as integrated control measures have been advanced , centering around japan . since 1996 , guidelines for the treatment of human ae are suggested and documented as a manual   and have recently been updated by who - iwge . the rules have been set : radical surgery is the first choice in all cases suitable for total resection of the lesion ; benzimidazoles as anthelmintic drugs are mandatory in all patients , temporarily after complete resection of the lesions , and for life in all other cases . interventional procedures should be preferred to palliative surgery whenever possible . in our patient , 2 times radical operations were proceeded because hepatic malignancy could not continuously excluded . albendazole has an efficacy similar to mebendazole , the first successfully used benzimidazole derivative   together with some pharmacokinetic advantages . she has been visiting regularly for radiologic follow - up , but till now no remarkable changes have been reported . here , we report a case of human ae , representing unusual hepatic mass on clinical examination which showed necrosis with numerous sterile cysts and granulomas on pathologic examination , in a non - endemic area with uncertain infection route .
human alveolar echinococcosis ( ae ) , a hepatic disorder that resembles liver cancer , is a highly aggressive and lethal zoonotic infection caused by the larval stage of the fox tapeworm , echinococcus multilocularis . 
 e. multilocularis is widely distributed in the northern hemisphere ; the disease - endemic area stretches from north america through europe to central and east asia , including northern parts of japan , but it has not been reported in korea . herein , we represent a first case of ae in korea . 
 a 41-year - old woman was found to have a large liver mass on routine medical examination . 
 the excised mass showed multinodular , necrotic , and spongiform appearance with small irregular pseudocystic spaces . 
 microscopically , the mass was composed of chronic granulomatous inflammation with extensive coagulation necrosis and parasite - like structure , which was revealed as parasitic vesicles and laminated layer delineated by periodic acid - schiff ( pas ) stain . 
 clinical and histologic features were consistent with ae . 
 after 8 years , a new liver mass and multiple metastatic pulmonary nodules were found and the recurred mass showed similar histologic features to the initial mass . 
 she had never visited endemic areas of ae , and thus the exact infection route is unclear .