cystic echinococcosis ( ce ) , also known as cystic hydatid disease is a parasitic infection endemic in many parts of the world . these are dogs ( definitive host ) and sheep or other domestic herbivores ( intermediate hosts ) with humans being accidental intermediate hosts . the adult worm develops in the small intestine of the definitive host , producing eggs which are excreted in faeces . egg ingestion leads to release of the embryo into the duodenum of the intermediate host with penetration of the intestinal wall leading to spread via the portal circulation . development of the larval stage occurs most frequently in the liver with protoscolices being produced . humans become infected by ingesting eggs of the parasite via infected foodstuffs or via contact with definitive hosts . patients with liver involvement are often asymptomatic , but where symptoms do occur they may present with vague abdominal pain , a secondary liver abscess , cholestatic jaundice or cyst rupture with or without anaphylaxis . we present a case of anaphylaxis secondary to trauma in previously unrecognised cystic hydatid disease . a 24 year old turkish male presented to his local emergency department after being assaulted . he had no known allergies . on admission he was tachycardic and had increasingly severe abdominal pain . a ct scan revealed a large mass in the right lobe of the liver with associated haemorrhage . urgent transfer to our liver intensive care unit ( litu ) was arranged with packed cells , fresh frozen plasma ( ffp ) and platelets all being transfused . he was noted to be erythematous and was suspected to have had a drug or transfusion reaction and thus received chlorphenamine . repeat ct scan and angiography ( figures 1&2 ) revealed a 17 cm mass occupying the right lobe of the liver with evidence of intrahepatic arterial and portal venous contrast extravasation . there was disruption of the normal right portal venous anatomy with the left portal vein being visible but displaced . indirect portography demonstrating a disruption of the intra hepatic right portal vein with extravasation of contrast into a hepatic mass . on return to litu he developed acute respiratory distress with a respiratory rate of 40 breaths per minute , saturation of 88 - 90% and was again erythematous . he was intubated and ventilated , but despite this he continued to deteriorate with a silent chest on auscultation . intravenous and nebulised adrenaline , salbutamol , magnesium sulphate and ketamine were all required to stabilise his condition . the right and left lobes of liver were grossly abnormal with a haematoma behind the porta hepatis and an attenuated portal vein ( pv ) . on inspection one further short episode of wheeze was effectively managed and he was transferred to the ward . biopsies showed irregular liver architecture with fibrosis indicating a chronic process ( figure 3 ) . higher magnification identified a parasite ( a hydatid protoscolex ) within a hepatic venule ( figures 4&5 ) and a diagnosis of hydatid disease ( echinococcus granulosus ) was made . he was treated with albendazole 400 mg bd and discharged home on day 16 . a liver biopsy showing fibrotic change within and outside the portal tracts . higher magnification h&e stained image showing a hepatic venule containing a characteristic echinococcal protoscolex with hooklets visible in section . elective endocystectomy was performed 6 months after discharge with histology showing no viable germinal membrane or protoscolices . our local population is ethnically diverse but the patient had lived in the uk for six years prior to presentation and had been asymptomatic throughout . accidental traumatic peritoneal rupture with associated acute hypersensitivity reactions have been reported ( 1,2 ) with upper abdominal pain , a mass or symptoms related to mass effect being frequent presentations . total pericystectomy is considered the treatment of choice but anatomical difficulties , as exemplified in this case , can make this option difficult ( 2 ) . ruptured hydatid cysts require surgery to provide peritoneal toilet . conservative approach of de - roofing the cyst and either draining the residual cavity or obliterating it using omentoplasty or capitonage . percutaneous aspiration , injection and reaspiration ( pair ) is another technique employed ( 3 ) . a cochrane review of the pair technique with or without benzimidazole coverage concluded that it may be comparable or superior to surgery ( 4 ) . increasing experience of laparoscopic therapy in combination with albendazole therapy has been shown to be safe and efficient ( 5 ) . optimal treatment should involve pre and post resection albendazole ( 6 ) but complications such as abdominal pain , nausea , vomiting , jaundice , leucopenia and anaemia are described ( 7 ) . this is a rare case of anaphylaxis to cystic hydatid disease initiated by leakage into the vasculature following trauma . cases of anaphylactic shock have been reported as the only manifestation of hydatid disease in cases of rupture into the peritoneal cavity and is considered in endemic regions ( 1,2,8 ) . buyuk et al ( 9 ) reported a case where hydatid disease led to death with cyst content spreading into the bloodstream . peritoneal rupture of the cyst did not occur in our case but the hydatid protoscolex found within a hepatic venule ( figures 4&5 ) indicates that the patient had intravascular exposure to the parasite . lewall and mccorkell ( 10 ) classified echinococcal cyst rupture into direct , contained and communicating types . the communicating type consists of a tear of the endocyst with escape of contents via biliary radicles or bronchioles . no description of communication with the portal vein exists but the findings in this case and the autopsy report from buyuk et al ( 9 ) suggest the classification should be extended to include this scenario .
cystic echinococcosis also known as cystic hydatid disease is a parasitic infection endemic in many parts of the world . 
 humans are accidental intermediate hosts with cysts most commonly developing in the liver . 
 this case describes a rare presentation of hydatid disease following trauma to the liver . 
 intraparenchymal cyst rupture led to haemodynamic instability with release of the parasites protoscolices into hepatic venules producing severe life threatening anaphylaxis .