paraganglioma is a rare neuroendocrine neoplasm that may develop at various body sites like abdomen , thorax , head and neck .
majority of paragangliomas develop in abdomen while mediastinal paraganglioma is a rare mediastinal tumor.12 posterior mediastinum is the commonest site for mediastinal paraganglioma while anterior mediastinal localization is unusual.13 most paraganglioma are asymptomatic and present as painless mass .
endoscopic ultrasound ( eus ) features of retroperitoneal paraganglioma have been described4 while that of mediastinal paraganglioma have not been described . in this report
we describe the eus features of mediastinal paraganglioma in a patient who presented with cough and chest pain without any neuroendocrinal symptoms .
a fifty - six year old female presented with one month history of chest pain and cough .
the patient was not hypertensive and did not give any history related to neuroendocrinal hormone over secretion .
the mass was inverted triangular shape with bulging peripheries , situated between aorta and left pulmonary artery .
the mass was hypervascular in the center and the interface between the mass and vessels described was intact and there was no lymphadenopathy ( fig . 1 - 3 ) .
eus - guided fine needle aspiration ( eus - fna ) was done using a 22-g needle ( echotip , cook corporation ) .
slides were prepared and the material was air dried as well as alcohol fixed before sending for cytopathological evaluation ( fig . 4 , 5 ) .
good material was obtained on eus - fna , but three experienced cytopathologists gave three different reports ; final diagnosis of paraganglioma was only made on thoracoscopic biopsy and immunohistochemistry .
mediastinal paraganglioma is a rare mediastinal tumor.12 it constituted 0.3% of all mediastinal tumors in the series described by cesar et al.1 while no case of mediastinal paraganglioma was found out of 57 eus - fna done for mediastinal masses by zeppa et al.2 majority of thoracic paragangliomas occur in posterior mediastinum . out of 16 cases of thoracic paragangliomas reported by cesar
paragangliomas arise from parasympathetic or sympathetic ganglia located in ap window or posterior mediastinum.34 diagnosis of asymptomatic paraganglioma on any imaging modality is difficult . on fna cytology , it is difficult to give final diagnosis.4 in our patient also the tumor could be finally diagnosed only upon thoracoscopic biopsy and immunohistochemistry and the tumor was positive for chromogranin , synaptophysin and neuron specific enolase .
eus features of mediastinal paraganglioma are not described while only in one case eus features of retroperitoneal paraganglioma are reported.2 the situations in retroperitoneum and mediastinum are different .
retroperitoneum is a potential big space where tumor can grow freely to any size and can assume any shape while there is little space in mediastinum for tumor to grow and tumor may assume a particular shape . in the present case , there were certain features which were highly suggestive of paraganglioma .
it is inverted triangular shape with base of the triangle lying superiorly , because there is sufficient space in ap window where tumor can grow , and apex lying inferiorly , because the tumor has to grow in between the vessels .
besides , there were other features such as rich vascularity of the tumor , bulging peripheries , no invasion of vessels and absence of lymphadenopathy .
we analyzed our 50 cases of various mass lesions involving ap window and subcarinal space , and in none of the cases such typical eus features were seen .
growth in between the vessels without invasion of vessels was a typical feature of benign paraganglioma .
when such appearance is seen on eus imaging , diagnosis of paraganglioma is quite likely and eus - fna may be risky and may not provide final diagnosis .
 endoscopic ultrasound ( eus ) features of mediastinal paraganglioma have not been described . in this paper , we report a female patient presented with cough and chest pain without any neuroendocrinal symptoms . 
 final diagnosis of mediastinal paraganglioma was made on thoracoscopic biopsy and immunohistochemistry after eus - guided fine needle aspiration . 
 eus features of mediastinal paraganglioma are described . 
INTRODUCTION
CASE REPORT
DISCUSSION