echinococcosis in an important parasitic infection that is still a common health problem in undeveloped and developing countries ( 1 ) .
the right atrium , right ventricle , and liver have been reported as embolic origins of such cysts ( 4 ) . here ,
we present a case of embolism of a hydatid cyst inside the left main pulmonary artery .
the cyst was in the upper segmental branch of the lingular artery , and segmental and sub segmental branches of the lower lobe artery .
however , no hydatid cysts were found in other organs . this case is interesting because there are only a few cases in which isolated pulmonary artery hydatid cyst without other organ involvement has been reported in the literature .
we believe that this case is the first example of pulmonary artery hydatid cyst diagnosed by ebus .
she had no complaints of sputum , chest pain , or dyspnea , but she had a suspicious history of hemoptysis
she had a dog in her childhood and she also lived in the rural area .
no abnormal signs were observed on her chest radiograph . pulmonary function tests and laboratory test results were within normal limits except for eosinophilia and minimally elevated d - dimer in the blood test .
d - dimer level of the patient was 600 ng / ml , while normal limits are 0 - 500 . a negative d - dimer result may exclude pulmonary embolism , but there are many reasons that cause d - dimer elevation such as infection , trauma , deep venous thrombosis , and disseminated intravascular coagulation . in this case , the reason of elevated d - dimer was parasitic infection .
the patient was treated with 250-mg fluticasone dry powder twice daily in an inhaler and montelukast once daily under a suspicious diagnosis of allergic asthma ; she asked for a control examination 2 weeks later . at the control examination
thoracic computed tomography ( ct ) was performed to investigate the etiology of cough and her minimally elevated d - dimer level .
filling defects were observed inside the left main pulmonary artery , upper segmental branch of the lingular artery , and segmental and subsegmental branches of the lower lobe artery on her thoracic ct angiogram ( figure 1 a - d ) .
this finding at the main and superior branch of the lingular artery showed continuity with an 18  16 mm nodular opacity considered likely to be a cystic embolism . the right pulmonary artery and its branches were clear .
subcutaneous low - molecular - weight heparin anticoagulant therapy was administered on the basis of the suspicious diagnosis of pulmonary thromboembolism . left and right ventricular parameters on echocardiographic evaluation were normal .
no intracardiac thrombi , or any thrombosis in the deep veins of the lower extremities were observed .
clinical and radiological findings were not completely compatible with thromboemboli . because pulmonary artery filling defects appeared more well - circumscribed and smooth , and they showed continuity with an 1816 mm nodular cystic opacity different from usual features of emboli
, the other reasons such as pulmonary artery sarcoma and hydatid cyst causing filling defects in the pulmonary artery on ct were investigated .
so for assessment of the other differential diagnoses , the patient underwent endobronchial ultrasound ( olympus evisexera ii cv180 ) .
an anechoic cystic area was visualized inside the left pulmonary artery ( figure 2 ) .
we performed endobronchial doppler ultrasound to investigate whether it was a cystic lesion that was causing the filling defects inside the pulmonary artery .
doppler ultrasonography revealed a cystic formation that made the vascular filling defect inside the left pulmonary artery .
thoracic magnetic resonance angiography was performed to investigate the cyst in more detail and it revealed cystic formations in the left pulmonary artery ( figure 3 a - d ) .
the lesions were hyperintense both on t1-w and t2-w mri images that showed the liquid within the cyst was rich of protein . on mri examination ,
either distal branches of the pulmonary artery were not filled with contrast and showed cystic lesions in them .
the nature was the same in the lesions on the proximal branches of the pulmonary artery .
indirect hemagglutination and specific ige tests were performed to confirm the diagnosis of hydatid cyst ; both results were positive .
the patient was scanned for frequent locations of organ involvement of hydatid cysts , but no other cysts were observed .
the diagnosis of pulmonary artery hydatid cyst was decided by the patient s history of living in an endemic area , thoracic ct , mri and ebus findings and also positive serology tests .
the size of the cyst in the left pulmonary artery on control thoracic ct scans shrunk 7.9 mm in diameter after one year of albendazole treatment ( figure 4 a and b ) .
the liver ( 70% ) and lungs ( 25% ) are the organs most often affected .
although cardiac involvement is observed in only 0.2 - 3% of cases , early diagnosis and treatment are important ( 5 ) . in primary cardiac hydatidosis ,
larvae usually reach the myocardium via the coronary circulation , the pulmonary circulation , or a patent foramen ovale .
intestinal lymphatic vessels , thoracic duct , superior and inferior vena cava , and hemorrhoidal and pulmonary veins may be involved ( 6 ) .
a variety of cardiac sequelae including sudden cardiac death , massive pulmonary embolism , and pulmonary hypertension may be encountered clinically .
echocardiography , ct , and magnetic resonance imaging ( mri ) can be used to identify cardiac hydatidosis ( 7 ) .
hydatid cysts located in the pulmonary arteries are frequently the consequence of embolisms from primary cardiac locations ( 8) . in the present case , a hydatid cyst was located inside the left pulmonary artery and its branches , without any cyst in the heart or other organs .
intra - arterial hydatid cysts grow slowly into the lumen , ultimately occluding it . in the pulmonary arteries ,
this process may occur over a long period . because pulmonary arteries have adequate pulmonary perfusion through the bronchial arteries
symptoms can be observed when the cysts compress a vital structure or interrupt blood circulation , which may also lead to anaphylactic shock ( 9 ) .
, the cough might be the result of compression of the left lower bronchus by the cyst .
hydatid cysts usually have a characteristic appearance on mri ; an oval lesion hypo intense and hyper intense on t1-and t2-weighted images , respectively . in this case , the lesions were hyper intense both on t1-w and t2-w mri images that shows the liquid within the cyst was rich of protein ( 10 ) . in the differential diagnosis of pulmonary artery hydatid cyst , pulmonary thromboembolism ( fat , amniotic fluid , septic emboli , particulate material ) and primary arterial tumors such as sarcoma should be considered since they also make intraluminal defects ( 11 ) .
radiological findings and the patients clinical features help to make the differential diagnosis since patients with disseminated pulmonary artery thrombosis show a more aggressive clinical manifestation .
hydatid disease may involve the heart , including the left ventricle ( 60% ) , right ventricle ( 10% ) , pericardium ( 7% ) , pulmonary artery ( 6% ) , and interventricular septum ( 4% ) ( 12 ) .
because of the significant risk of cyst rupture and anaphylactic shock , surgery should be performed promptly after diagnosis .
echocardiography , spiral ct , mri , ct angiography , magnetic resonance imaging angiography , and conventional pulmonary angiography can be used for the diagnostic investigation of patients suspected of hydatid pulmonary embolism .
if there is no history of hydatid disease , its existence can be suspected based on the presence of anti - echinococcal antibodies and eosinophilia in blood tests ( 14 ) .
the present case had eosinophilia and positive indirect hem agglutination and specific ige test results .
imaging methods are sometimes limited by the small size of the lesion and the atypical images that are difficult to distinguish from abscesses or neoplasms .
routine laboratory diagnosis of hydatid cysts depends on detection of specific antibody response . according to who manual for hydatid cysts , ct findings alone allow a correct diagnosis of 61% hydatid cysts of the liver , lung , kidney , spleen and some other sites and
the correct diagnosis rate is 94% if ct is combined with serology ( 15 ) . according to a comma ,
the sensitivity and specificity of iha was 100% and 83.3 - 99% , respectively ( 16 ) .
however , it should be kept in mind that embolectomy of the hydatid cyst from the main pulmonary truncus increases morbidity and mortality ( 16 ) .
symptoms are usually absent or nonspecific and include chest pain , dyspnea on exercise , and fever .
eosinophilia occurs in 20% of the cases and may be associated with recent rupture ( 18 ) .
hydatid cysts can be solitary or multiple and vary in size ( 16 ) . in the present case , a cystic filling defect was found inside the main pulmonary artery and a solid defect was found inside the left lower intermediate artery .
rupture into the cardiac chambers occurs most often in the right ventricle and can cause anaphylaxis , or pulmonary or systemic embolism of the daughter cysts ( 19 ) .
repeated pulmonary emboli may produce pulmonary arterial hypertension and multiple lung cysts ( 20 ) . in the present case ,
left ventricular systolic function , the right atrium , and the systolic pulmonary artery pressure were normal and no intracardiac thrombus was found .
ebus is increasingly used for lung cancer staging and the assessment of sarcoidosis ( 21 ) .
it is useful for producing real - time images of both lymph nodes and pulmonary arteries ( 22 ) .
after one year of treatment with albendazole , in the follow - up thoracic ct scan , there was a decrease in the size of the cystic lesion in the left pulmonary artery . as a result
, albendazole treatment can be an alternative therapy for surgery especially for patients who reject operation .
 hydatid cyst ( hc ) is a parasitic disease that may involve many organs , especially the lung and the liver . 
 pulmonary artery location of the hydatid cyst is extremely rare , but it may cause life - threatening complications . 
 we report a case of a hydatid cyst that completely filled the left main pulmonary artery and its distal part without cardiac involvement . 
 thoracic computed tomography showed filling defects in the pulmonary arteries . 
 endobronchial ultrasound was performed for differential diagnosis and it showed a cystic lesion . 
 hydatid cyst - specific ige and hem agglutination test results were positive . in the literature , 
 cases like this in which the diagnosis of pulmonary hydatid cyst is made by endobronchial ultrasound are not usually seen . 
 although many imaging modalities such as plain chest radiography , cross - sectional imaging ( mdct and mri ) , echocardiography and conventional pulmonary angiography have been used in the diagnostic approach , we recommend endobronchial ultrasound for the differential diagnosis of cases with cystic formation . 
1. Background
2. Case Presentation
3. Discussion