hydatid disease ( hd ) , which is caused by echinococcus granulosus , is a common parasitic infestation especially in endemic regions such as the middle east , mediterranean , and south american countries . even though it mainly involves the liver , it has been reported in nearly all parts of the body . the incidence of the splenic cysts in hd varies from one series to another , ranges 0.54% of all cases of echinococcosis . however , one study showed that hd is common in jordan , but isolated spleen disease is described only in 2.5% of cases . symptoms of splenic hydatidosis is usually mild and is mainly caused due to pressure of adjacent organs such as colon / diaphragm or the presence of complications . cysts may become infected or may rupture into the peritoneal cavity , especially subcapsularly located cysts like our case . the hydatid fluid is antigenic and highly toxic and can cause a potentially fatal anaphylactic reaction in humans . herein , we describe an acute happening of anaphylactic shock due to a spontaneous rupture of the primary isolated hydatid cyst in a 57-year - old woman . a 57-year - old woman was admitted to the emergency department for diffuse maculopapular rashes on the whole body and anaphylactic shock . she had been complaining of sudden- onset of abdominal pain , dyspnea , pruritus , and urticaria . on physical examination , it revealed tenderness , guarding , and rigidity all over the abdomen . the patient recovered after emergency medications and then abdominal computed tomography ( ct ) revealed a splenic cystic lesion measuring about 9 6 cm in diameters and containing floating membranes . the anterior wall of the cyst showed discontinuity at a point [ figure 1 ] . then , the patient underwent a laparoscopic partial cystectomy and omentoplasty , since the spread of the disease into the peritoneal cavity of lesions was strong contraindications for a radical surgical approach . at the time of laparotomy the postoperative course was uneventful , and the patient was discharged 10 days after the surgery . we applied albendazole , 10 mg / kg / day for 6 months , and the patient was followed up with ct that displayed no recurrence of the disease during a follow - up of 6 months [ figure 3 ] . computed tomography showed floating membranes in the splenic cystic lesion ( long arrow ) , rupture point ( short arrow ) , and perisplenic fluid ( open arrow ) intraoperative photograph shows a ruptured outer membrane of an echinococcal splenic cyst follow - up computed tomography image shows no residue or recurrence in spleen with omentopexy ( star ) hydatid disease is a parasitic infestation caused by the larva of echinococcus , more frequently encountered in endemic areas such as mediterranean countries , south america , africa , and middle east . even though various theories have been published about the pathophysiology of splenic hydatidosis , the most suitable study was published by bourgeon et al . the development of echinococcal cysts in the spleen is uncommon because hexacanth embryos are usually trapped in the liver ( first lemman 's filter ) or lung ( second lemman 's filter ) , but will be trapped in the splenic capillaries once in the systemic circulation . splenic echinococcosis may also occur by retrograde reach from the liver to the spleen via the portal and splenic veins in portal hypertension . the spleen may also be affected due to rupture of a hepatic echinococcal cyst into the peritoneal cavity . patients remains asymptomatic for 520 years before the diagnosis , and approximately 30% of splenic cysts are asymptomatic . in these asymptomatic patients , when the cyst reaches a huge size , it presents with a painful mass in the left upper quadrant . if the cyst is infected , or abscess formation has been occurred , left upper quadrant pain , fever , and leukocytosis develop . rupture into the abdominal cavity is a rare but serious complication because the hydatid fluid is antigenic and highly toxic . anaphylactic reaction to the hydatid cyst usually occurs after microscopic or macroscopic rupture of the cyst and leakage of contents into the peritoneum or blood circulation . the response can be vary from a mild hypersensitivity reaction to a fatal anaphylactic shock . rupture of a splenic hydatid cyst occurs commonly secondary to trauma , but it may also rarely occur spontaneously such as our patient . the diagnosis is mainly historical and geographic background of the patient , physical examination , serology , and visualization of peripheral calcification or daughter cysts within the large cystic lesion or coexistent cystic lesions with radiologic examination in the liver or other organs . ultrasound and ct imaging have been used successfully in the detection of a ruptured hydatid cyst . at present , ultrasonography is the most valuable and most widely available imaging modality for the diagnosis , classification , and follow - up of splenic hydatid cysts . ct is more sensitive than plain films or sonograms in depicting subtle cyst wall calcification . ct is an important imaging modality to have the actual number and location of the cysts not only in the spleen , but also in the abdomen . the presence of a cyst in the spleen of a patient who developed anaphylactic reaction with detection of membrane - like structures inside the cyst and discontinuity of the wall are considered diagnostic for ruptured hydatid cysts such as our patient . surgical excision is still the only curative treatment , but good results have been reported with albendazole administration . medical treatment is indicated in cysts inaccessible for surgical removal or as a complementary therapy to prevent recurrence . the surgical procedure consists of removing the cyst and possible daughter cysts spilled into the abdominal cavity in combination with peritoneal washing . total splenectomy is advocated by the majority of surgeons , especially for patients with large cysts located centrally or near the hilus , since it gives rise to minimal risk of recurrence . laparoscopic or laparoscopically assisted splenectomy has also been successfully used for echinococcal disease of the spleen . atmatzidis et al . showed that the recurrence rate after total splenectomy was not significantly different compared to spleen - preserving surgery , and the complication rate and hospital stay were also comparable between these two groups . in summary , the hydatid cyst is still a serious health problem in endemic areas as well as in our country . although the liver and lung are the most frequently involved organs , primary splenic hydatidosis is quite rare . hydatid cyst must be considered in the differential diagnosis of patients presenting with anaphylactic shock in areas where the disease is endemic and even in nonendemic .