only a few cases of pulmonary vascular tumors diagnosed using endobronchial ultrasound - guided transbronchial needle aspiration ( ebus - tbna ) have been reported in the literature .
they frequently present as filling defects in the pulmonary vasculature on computed tomography ( ct ) making it challenging to distinguish between vascular tumor and thrombotic emboli .
although fluorodeoxyglucose - positive emission tomography ( pet ) scan may reportedly help differentiate malignant growth from benign emboli , pet scans are not routinely performed for this purpose . increased uptake on the pet scan increases the malignant suspicion of vascular tumors but in most cases
ebus - tbna of mediastinal and hilar lymph nodes has proven value in diagnosis and staging for lung cancer .
in addition , ebus - tbna may provide an opportunity to identify and sample endovascular abnormalities in the mediastinal and hilar area .
a 43-year - old white male was diagnosed with leiomyosarcoma of proximal left thigh involving femoral vessels 2 years back .
he was found to have pulmonary embolism involving right pulmonary artery for which he was started on anticoagulation and an inferior vena cava filter was placed prior to surgery . despite being on anticoagulation postoperatively , serial surveillance imaging continued to show persistent  thrombus .  eventually , an interval increase in size of the filling defect in right main pulmonary artery extending to the right lower lobe pulmonary artery was noted on contrast - enhanced chest ct [ figure 1 ] . at this point ,
intravascular metastatic tumor was suspected and the patient was referred to our interventional pulmonary service for diagnostic evaluation .
the patient did not have any other imaging studies such as pet scan or magnetic resonance imaging of the chest .
ebus ( bf - uc160f - ol8 ; olympus , tokyo , japan ) procedure was performed under general anesthesia . with the ultrasound and color flow doppler ,
an endovascular hyper - echoic lesion was identified in right pulmonary artery [ figure 2 ] .
only one endovascular lesion was identified , which extended to the right lower lobe branch of the pulmonary artery .
because of the nature of the lesion 's extension in the pulmonary artery , it was not possible to accurately size it but it was estimated to be around 20 mm in the largest diameter .
ebus - tbna of this lesion using the 22 gauge ebus needle ( olympus , na-201sx-4022 ) was performed under general anesthesia with laryngeal mask airway using propofol intravenous drip and fentanyl intravenous intermittent injections .
a core biopsy was obtained using the 22 gauge ebus needle and a total of five passes were performed during this procedure .
rapid - on - site evaluation of fixed slides was bloody , and no malignant cells were identified .
the procedure was performed without any complications and cytopathological and immunohistochemical evaluation confirmed the diagnosis of metastatic leiomyosarcoma [ figure 3 ] . the patient was started on gemcitabine plus docetaxel combination chemotherapy .
( a ) chest computed tomography ( ct ) image showing right pulmonary artery filling defect ( arrow ) diagnosed as pulmonary thrombotic emboli 2 years ago .
( b ) chest ct 2 years later showing enlarged right pulmonary artery filling extending to the right lower arterial branch consistent with vascular tumor ( arrow ) ( a ) endobronchial ultrasound ( ebus ) image of the right hilar area showing an vascular tumor of the right lower lobe pulmonary artery ( arrow ) .
( d ) ebus - guided transbronchial needle aspiration ( arrow ) of the right pulmonary artery tumor .
the color doppler was used to ensure sampling the tumor area with the least blood flow ( a ) this is the tissue core biopsy of the right pulmonary mass lesion showing cells with abundant eosinophilic cytoplasm and spindled nuclei ( h and e , 200 original magnification ) .
( b ) these cells cytologically shows fine granular chromatin without prominent nucleoli ( papanicolaou stain , 600 original magnification ) .
( c ) immunohistochemical stains for smooth muscle actin shows strong immunoreactivity in these cells ( sma , 400 original magnification ) .
( d ) immunohistochemical stains for desmin also shows strong positivity in these malignant cells ( desmin , 200 original magnification )
historically , most cases of pulmonary artery tumors were diagnosed with surgery or during postmortem examination .
successful diagnosis of primary pulmonary artery leiomyosarcoma with catheterization and biopsy has also been reported . in the last few years , several cases of primary and metastatic pulmonary artery tumors diagnosed by ebus - tbna have been reported without any procedure - related complications .
although pulmonary artery hematoma has been described from ebus - tbna , the pulmonary artery was inadvertently punctured in that case during a routine biopsy of mediastinal lymph node .
in addition , there have been reports of using ebus - guided trans - pulmonary vascular lymph - node sampling without any complications . here , we present the first case of metastatic leiomyosarcoma of pulmonary artery diagnosed with ebus - tbna .
the case reported is a clear example of the challenges in diagnosis of pulmonary artery tumors due to their endovascular location and the potential risk of bleeding .
the use of color flow doppler during ebus - tbna of pulmonary vascular tumor is essential to avoid area of higher blood flow and to perform the biopsy in the tumoral area of least blood flow . given the potential higher risk of bleeding , anticoagulation or clopidogrel therapy should probably be discontinued prior to this procedure .
clinically , the importance of high index of suspicion is also demonstrated as the patient was initially diagnosed with pulmonary embolism .
misdiagnosing patients with pulmonary artery tumor emboli as thrombotic emboli can result in delaying effective tumor therapy with chemotherapy or surgery .
the diagnosis of pulmonary embolism in patients with malignant diseases can be challenging especially in ill patients where the wells score is already high .
our patient was asymptomatic , and the chest imaging was performed as part of surveillance and staging of his sarcoma .
intravascular metastasis was suspected as an alternate diagnosis after the presumed failure of anticoagulation therapy and increased of the pulmonary artery lesion size .
ebus - tbna is a safe procedure and serious complications are extremely rare . until now
, ebus - tbna of the pulmonary vascular lesions did not report any serious complications .
ebus - tbna seems to be a safe , feasible , and minimally invasive tool for the diagnosis of vascular tumors such as metastatic pulmonary artery leiomyosarcoma .
 leiomyosarcoma of the pulmonary vasculature is an extremely rare condition that has not been previously diagnosed by endobronchial ultrasound ( ebus ) bronchoscopy . 
 we present the case of a 43-year - old white male with a history of leiomyosarcoma who was diagnosed with pulmonary embolism 2 years ago . as the filling defects on follow - up chest computed tomography continued to worsen despite anticoagulation , 
 ebus - guided transbronchial needle aspiration ( ebus - tbna ) of the right pulmonary artery lesion was safely and successfully performed . 
 cytopathological examination revealed the  
 thrombus  to be metastatic leiomyosarcoma . in experienced hands , and carefully selected cases , ebus - tbna seems to be a safe and effective in diagnosing thoracic endovascular lesions . 
INTRODUCTION
CASE REPORT
DISCUSSION
CONCLUSION