bronchogenic cysts are rare developmental aberrations of the primitive foregut which occur between the third and the seventh week of embryonic life , through abnormal budding . depending on the location of the abnormal budding they are associated to cervical , thoracic or abdominal   structures . therefore the most common location of bronchogenic cysts is the posterior mediastinum ; retroperitoneal location is rare . it has been postulated that the aberrant bud detaches from the primitive foregut , then migrates towards the abdomen prior to the fusion of the diaphragm , resulting in a retroperitoneal bronchogenic cyst [ 3 , 4 ] . the differential diagnosis includes adrenal adenomas , pancreatic cysts and pseudocysts , mucinous cyst adenomas , pseudopapillary neoplasms , cystic teratomas and urogenital cysts . the indication for surgery is controversial in these cases , but the uncertainty of the diagnosis after imaging supports the indication for surgery and histological workup . a 42-year - old woman was admitted to the hospital with sharp continuous epigastric pain of 2 months duration with postprandial augmentation . she had neither a history of previous pancreatitis nor hypertension or clinical signs for hypercortisolism , but irregular vaginal bleedings . serum laboratory tests showed signs of inflammation and a ct scan of the abdomen ( fig . 1 ) showed a cystic mass of 5  3.6  4 cm located adjacent to the pancreatic tail and left adrenal gland . endoscopic ultrasonography with fine needle aspiration was performed and showed a polycystic structure with anechoic and hyperechoic portions . microbiological analysis and analysis for lipase were negative . there were no malignant cells , but carcinoembryonic antigen ( cea ) was elevated with 3,777 g / l ( normal < 5 ) in the cyst , but normal in the serum with 4.3 g / l . because of the association to the adrenal gland and the history of vaginal bleeding , endocrine evaluation for adrenal hypersecretion was performed . all tests were normal , including renin and aldosterone , plasma and urine catecholamines , metanephrines , estradiol , luteinizing hormone , follicle - stimulating hormone and cortisol . the cystic and encapsulated lesion with smooth and clear boundaries was not discriminable from the left adrenal gland . the pancreas , stomach , diaphragm and aorta were adjacent to the cyst , but not involved . postoperative recovery was uneventful . in the pathological workup the cyst had a smooth inner lining and contained a grey viscous mass . microscopically , it consisted of ciliated , respiratory epithelium , seromucous glands and fully developed cartilage , without any malignant or dysplastic cells ( fig . the adrenal gland was histologically inconspicuous and had no direct contact or connection to the cyst . the most common location is the posterior mediastinum and related to the lung or the tracheobronchial system . when a bronchogenic cyst is located retroperitoneally , the localization in 80% of published cases is left to the midline and close to the distal pancreas , spleen and left adrenal gland as in the present case . the pathogenesis is not fully understood , but it was assumed that a lack of closure of the pleuroperitoneal channel in conjunction with abnormal budding from the primitive foregut may lead to migration of tracheobronchial tree bud to the abdominal cavity . if the cyst is in relation with the tracheobronchial tree , it causes recurrent respiratory infection . although most abdominal cases are diagnosed incidentally , they may present with epigastric or back pain . when detected most of them measure < 5 cm , so they are too small to be symptomatic , unless they are secondarily infected or compress neighboring organs . the fine needle aspirate of the content was sterile , but this examination was performed after the onset of antibiotic treatment . to detect a bronchogenic cyst , ct scan and mri are the best imaging modalities . in the ct scan the lesions are mixed cystic - solid , sharply defined , hypoattenuating and homogenous possibly with calcifications . in t2-weighted mri these features are shared with other possible pathological entities : adrenal adenomas , pancreatic cysts and pseudocysts , mucinous cystadenomas , pseudopapillary neoplasms , cystic teratomas , urogenital cysts , epidermoid cysts , cystic type of lymphangioma or stromal tumors . because of the close anatomical localization to the pancreas and the differential diagnosis of several pancreatic cystic lesions , we used endoscopic ultrasound and fine needle aspiration as a diagnostic step . for pancreatic cystic lesions , the information about the presence of malignant cells , mucus , lipase , cea and ca19 - 9 help to decide whether surgery is indicated . in our patient , as bronchogenic cysts contain a lot of mucus , it is consistent that they contain cea , as in our case . very rarely the cea can be measured systemically , but in most cases there are no specific markers in the serum by which to detect a bronchogenic cyst . because of localization close to the adrenal gland , an endocrine differential diagnosis is often considered . therefore an endocrine workup is often performed ; nevertheless it does not help the diagnostic process . due to the impossibility to exclude the presence of a neoplastic disease once surgical treatment has been chosen , a laparoscopic approach is state of the art . potential complications often present at the time of diagnosis are secondary infection , bleeding and compression of adjacent organs . histologically bronchogenic cysts are defined as the simultaneous presence of ciliated respiratory epithelium , mucinous glands and well - differentiated cartilage . 2 ) . we did not find smooth muscle cells , which have been found in other cases . additionally , the cyst 's content was probably an old hematoma , which might have occurred at the time of endoscopic fine needle aspiration . the initial ct scan showed a cystic lesion with a density of 6 hounsfield units ( hu ) . it showed a density of the cyst content of 102 hu , which is in accordance with the density of a hematoma . although very rare , bronchogenic cysts should be considered in the differential diagnosis of a retroperitoneal mass , particularly those left to the midline .
retroperitoneal location of bronchogenic cysts is extremely rare . 
 most commonly they are encountered in the posterior mediastinum . 
 bronchogenic cysts arise from developmental aberrations of the tracheobronchial tree in the early embryologic period . 
 we report a 42-year - old female patient with a retroperitoneal bronchogenic cyst in the left adrenal region . 
 she was admitted to our hospital with epigastric pain and subsequently underwent ct of the abdomen . 
 the examination revealed a mass related to the left adrenal gland . 
 endocrine tests for adrenal hypersecretion were negative . because of the uncertain entity 
 , laparoscopic adrenalectomy was performed . 
 pathological examination revealed a bronchogenic cyst in proximity to an inconspicuous left adrenal gland . 
 although very rare , bronchogenic cysts should be considered in the differential diagnosis of retroperitoneal cystic lesions and surgical resection pursued for symptom resolution and to establish a definitive histology .