hemangiomas are categorized as racemose , capillary , cavernous , and venous , according to the size of their vascular spaces .
cavernous and venous hemangiomas have low blood flow , because they lack arterial or capillary components .
histopathologically , venous hemangiomas contain dilated vessels with thick , fibrous walls , whereas cavernous hemangiomas have capillary - sized vessels lined by flat endothelial cells .
we report the first case of a venous hemangioma of the pps and discuss its typical radiographic findings .
a 49-year - old female patient was referred for evaluation of swelling in the right submandibular region .
she had swelling for the first time 3 weeks earlier , and it had not improved after medical treatment .
clinical examination revealed a soft mass in the right submandibular region and a bulge at the right lateral pharyngeal wall . a contrast - enhanced computed tomography ( ct ) scan revealed a cystic lesion , 4.63.0 cm , with contrast non - enhancement in the parapharyngeal space ( pps ) .
mri showed a well - circumscribed non - enhancing mass with high signal intensity on t2-weighted images ( fig .
the cystic lesion of the pps was surgically removed using a transcervical approach . during surgery
the lesion bled profusely , but the mass was bluntly dissected from the surrounding structures .
the surgical specimen , measuring 4.34.52 cm , showed a pale - to - dark brown soft cut surface with a blood - filled spongy vascular lesion .
microscopic examination revealed blood - filled sinusoidal spaces with large irregular lumens and thick walls lined by endothelial cells ( fig .
postoperative recovery was uneventful , and there has been no evidence of cranial nerve palsy or tumor recurrence after one year .
pps has a complex anatomy and close proximity to vital anatomical structures , with which it may become involved by various pathological processes . presenting symptoms of pps tumors may be attributed to the size of the mass and compression of neighboring structures ( 1 ) .
we had difficulty with the preoperative diagnosis , due to the absence of typical symptoms or signs of a vascular lesion in the pps , such as pulsation or bruit .
fine - needle aspiration cytology ( fnac ) was also not helpful in reaching a diagnosis .
although an exact tissue characterization of hemangioma in the pps could not be made on fnac , contrast - enhanced ct and magnetic resonance imaging ( mri ) should be included in differentiating these lesions from other tumors of the pps . in general ,
mr imaging is superior to ct imaging in its ability to ascertain the soft tissue characteristics of pps tumors ( 2 ) .
changes in the blood flow dynamics within a hemangioma result in thrombus formation and phleboliths ( 3 ) .
phleboliths are calcified nodules that can be regarded as a characteristic property of venous or cavernous hemangiomas .
ct with contrast is an excellent imaging technique for revealing phleboliths . although mri is not sensitive for the detection of small amounts of calcification , large amounts of calcification show discrete low signal intensity on all pulse sequences
mri can produce high signal intensities , representing the blood , as well as focal heterogeneities , representing areas of thrombosis , fibrosis , or calcification ( 4 ) .
although mri is very useful for the detection of vascular lesions , the detectability of phleboliths on ct images is superior to that by mri .
some reports have shown that plain x - ray films may also reveal calcified lesions .
when imaging shows calcification in the pps , the differential diagnosis may include pleomorphic adenoma of the deep lobe of the parotid gland and metastatic thyroid carcinoma of the pps .
pleomorphic adenoma with foci of chondroid or osteoid stroma can demonstrate opacities on imaging , but usually shows minute , scattered flecks .
additionally , in cases of metastatic thyroid carcinoma of the pps , large flocculent calcification is seen on ct images ( 5 ) .
venous hemangioma can not be clinically or radiologically differentiated from cavernous hemangioma , because of their similar characteristics .
however , perfusion and blood pool scintigraphy has been demonstrated to have high sensitivity for detecting head and neck hemangioma , and can also differentiate between cavernous and venous hemangiomas ( 6 ) .
they tend to be larger and less well circumscribed , and show no tendency to regress ( 7 ) .
attention needs to be given to the tumor location , extent , growth rate , and accessibility as well as the patient 's age and esthetic concerns .
the excision of large tumors in the pps can be challenging , given the risk for severe hemorrhage and nerve injury .
a surgical approach should be chosen according to the tumor size and location , its relationship to the great vessels , and any suspicion of malignancy .
generally , hemangiomas in the pps , including venous hemangioma , can be resected by using a transcervical approach .
profuse bleeding often occurs during surgery , but after all of the pathology has been removed , the bleeding will cease . when surgery is impossible , the use of corticosteroids , cryotherapy ,
feeding vessel ligation , embolization , and fibrosing agents can be considered as alternatives ( 8) . in summary , we present the first reported case of venous hemangioma occurring in the parapharyngeal space . considering that a presumptive diagnosis of most pps tumors can be made based on imaging studies , preoperative imaging findings are very important in approaching these lesions .
it may be that multiple , spotty , calcific nodules , 13 mm in size , within a cystic lesion on ct images indicate the pathognomonic finding of hemangioma in the pps .
 a hemangioma of the parapharyngeal space ( pps ) is an extremely rare tumor and is responsible for 0.5 - 1% of all tumors occurring in the pps . 
 we report a case of pps venous hemangioma in a 49-year - old woman presenting with diffuse swelling in the submandibular region . a preoperative computed tomography ( ct ) scan showed a cystic mass with multiple calcifications in the pps . 
 the calcific nodules were round and about 2 mm in diameter . 
 the hemangioma was completely resected via a transcervical approach . during surgery 
 , we found several calcific nodules , which represented phleoboliths or areas of thrombosis with dystrophic calcification . despite its rarity , 
 a venous hemangioma of the pps should be considered in a differential diagnosis when a cystic mass with calcification is found by ct scan . to our knowledge , this is the first reported case of a pps venous hemangioma ; we describe its pathognomonic findings on imaging . 